Certain features of democratic regimes, such as the separation of legislative, executive and judicial powers, are in themselves absolute values, in the sense that it is an absolute truth that all regimes of government should include them.
No opposition to democracy is legitimate, and there is no freedom to oppose democracy. To oppose democracy is wrong, and every opponent of democracy is motivated by a personal choice for evil.
No opposition to the separation of powers, or any other constitutional doctrine which is a necessary component of a democratic regime, is legitimate.
Democracy is perfect, in the sense that no other regime of government can be better than democracy. No historically existing regime of government has been superior to democracy, and no thinkable or possible future regime of government will be superior to it. In this respect, the historical succession of regimes of government has reached its only morally acceptable end point, with the emergence of liberal democracy. There should be no further innovation in regimes of government, apart from the internal improvement of democracy.
Democracy is a moral norm in itself. The outcome of the democratic process is good in itself, in the sense that there are never any external ethical norms which justify its reversal by non-democratic means. People may oppose the outcome of the democratic process, but only within that process itself. If their opposition fails to affect the outcome, then they must accept that outcome, even while they continue their opposition.
Totalitarianism is wrong in itself, because of the totality, and regardless of the basis of the totality. A 99% evil democratic society is better than a 100% good totalitarian society. However, a democracy is never totalitarian, even if it is totally democratic, and even if this is enforced against the will of the population.
A democracy is always preferable to totalitarianism, regardless of the the outcomes of the democratic process, and regardless of how much suffering or evil they entail. A democratic society, where life entails so much suffering that the entire population commits suicide, is still far better than a totalitarian society where everyone is happy.
Consequently, there can be no freedom to choose a totalitarian system of government, or a totalitarian society, and this choice is evil in itself. All force may be used to prevent this choice from being effected, and those who choose totalitarianism may legitimately be killed.
No non-democratic state should exist. No society which is not liberal-democratic should exist. The fact that a state is non-democratic justifies, in itself, a war of conquest against that state, by any or all democratic states.
Any degree of repression is justified, if that is necessary to impose democracy on a specific territory.
No scientific or philosophical debate on the existence and validity of human rights is valid, and such debate may legitimately be suppressed.
There is no freedom to renounce human rights, even in cases where their effect on the individual is negative and harmful.
There is no political freedom, or freedom of conscience, in respect of human rights. Everyone must accept them, and all necessary coercion to enforce this acceptance is legitimate.
The moral obligation to accept inequality, in cases where it is the outcome of liberal-democratic process, is absolute. No inequality is so great that it justifies terrorism or totalitarianism.
This obligation to accept inequality applies to inequalities between states and their populations, both among democratic states, and between a democratic and a non-democratic state. The democratic process within a state determines whether it chooses to share its wealth with other states, and their populations. No democratic state has any claim on the wealth of another democratic state, if that state democratically chooses not to share it. A fortiori, no non-democratic state has such a claim either.
Democracies choose their own members. No individual, who is not a citizen of a democratic state, has any claim on participation in its democratic process, in the form of citizenship and the accompanying right of residence in the state. Consequently, there is no obligation on democracies to accept immigration, and if the outcome of the democratic process is to restrict or even ban immigration, then this must be accepted.
The non-citizen in a poor country therefore has no individual claim on participation in the prosperity of a wealthier democratic society by migration, no matter how acute their poverty. A democracy may legitimately exclude such a person, even if the exclusion results in their death.
Long-term development, within poorer states, is the primary answer to global inequality. A coerced programme of global redistribution, which transfers wealth from rich states, in defiance of the outcome of the democratic process within those states, is morally unacceptable. It is better that a billion people starve on a planet of liberal democracies, that that their lives are saved by one or more totalitarian regimes, or by terrorist coercion of democracies.
The Euston Manifesto names two specific targets: 'jihadists' and 'Baathist thugs'. They also specifically name Stalinists, Maoists, and "illiberal theocrats" as their enemies. At one point the Manifesto distinguishes between totalitarianism and "other tyrannical regimes", but the rest uses 'totalitarian' as a general term for all non-democracies. (Neoconservatives often use the terms 'totalitarian', 'autocratic' and 'authoritarian' in this way, as category terms including all non-democracies). What is not in doubt, is that the authors of the manifesto see all these ideologies, and the people who hold to them, as their enemies.
A hypothetical example will clarify the position. Suppose that tomorrow a large island is discovered in the Atlantic, 500 km west of Portugal. It has 10 million inhabitants, and they are all totalitarians. That is, totalitarianism is their only belief system, and they have no other religion. Consequently, the island has a totalitarian regime. Since their existence was unknown, they have no contact with any other country, and consequently they have never harmed any country, any state, or any inhabitant of any other state. Now what do Geras and Johnson say about such an island? Their position is, that liberal-democratic states have a moral entitlement to invade the island, and enforce a regime change to a democratic regime. Not only an entitlement, but an obligation, since the totalitarian regime constitutes unfreedom, and there is an obligation to liberate. They say that the consent of the islanders is not required. They also disregard, in this context, any moral imperfections of the democratic states. So they would support a US-led invasion of the island, with participation by British forces, to democratise the country. They would support this, even if the islanders resist, even if every single islander resists and if they will not surrender even when surrounded by coalition forces. They see such an invasion as legitimate, even if 60% of the island's population is killed during the liberation.
The example of the hypothetical island is borrowed from the legend of Atlantis, and Thomas More's Utopia (which some people see as an early work of totalitarian ideology). The point is that Geras and Johnson are prepared to kill people who have never harmed them in any way, for the purpose of imposing their liberal ideology on those people, and that they ethically justify this by claiming that it is a liberation. Are Geras and Johnson good people?
Now, politics is about killing people. In the real world, people don't live on isolated islands, with the population neatly sorted by ideology and belief, so that you never have to disagree with your neighbours. In the real world there are enemies. If you are not prepared to kill your enemies, then they will ultimately rule over you. Democracy exists by virtue of the readiness of democrats to kill non-democrats. Conversely, non-democracy exists because non-democrats are prepared to kill democrats. The wars associated with such conflicts of ideology are not the product of a brutal human nature, but derive from the condition of enmity - which is itself part of the human condition.
So it isn't surprising, that the authors of the Euston Manifesto want to kill their anti-democratic enemies. It is surprising that they can advocate that openly, and still get away with it, in the sense that few people even notice it. I am not familiar with the details of British politics, so I do not know all their possible targets - most would be Islamists. However one specific case is clear: the authors of the Euston Manifesto advocate the killing of members of Hizb ut-Tahrir, which actively seeks the overthrow of liberal democracy, the establishment of a single Caliphate, and the expansion of that caliphate by jihad.