I can't speak for all the anti-Ukrainian war posters here. But there is a clear contingent on FR who pretend this is about not getting involved in a foreign war yet tend to justify everything Russia does. Make no mistake Russia does have a policy of trying to influence people over the internet and that there are some of their operatives here. The same people who will (rightly) complain about the Western bias in our news will post Russian sources without batting an eye.
There might be some who are legitimately "against foreign intervention" full stop. The trouble is their words belie their intent.