They are arguing in bad faith and they know it. The peace-absolutism is in a long tradition of pro-Soviet propaganda, where the only obstacle to eternal world peace was countries (particularly those opposing the Soviet Union) having any military at all. (Soviet Union was of course allowed to have a strong military to “protect” itself from Western, particularly US, “aggression”).

All of the calls for “peace” and “diplomacy” now are exactly the same: calls to stop actively resisting Russian aggression, and in the longer term to destroy your capability of being able to resist in the first place. And, if possible, to simply roll over to all Russian demands because you aren’t being “diplomatic” otherwise.

War, in this propagandistic view, is only caused by the country being invaded defending itself; after all, if they simply allowed Russia to take over, there would be no war. In the best case, the situation would have been solved through “diplomacy”, i.e. simply agreeing to all Russian demands. That way war would have been avoided, right?

And because no sensible person wants war, the leaders saying “no” to Russian demands (and who therefore must not want diplomacy, right?) must want war either because they’re corrupt and want to profit off of the war, because they’re “russophobic” “nazis” who “unreasonably” hate Russia, or because they’re being used as pawns by someone else, most likely the US. Because no one wants war, and therefore should be willing to conduct diplomacy over any questions (i.e. roll over to Russian demands) if they were not being manipulated in some way. And that is why poor Russia is “forced” to invade countries because of the US and the West, because being US pawns they are not willing to be diplomatic (i.e. agree to all Russian demands).

Anyone in the West supporting the invaded country is therefore a “warmongerer” if they do not support “diplomacy” (= letting Russia have whatever they want). Because there would be no war if Russia could just do whatever they want with no resistance.