https://www.scribbr.com/fallacies/slippery-slope-fallacy/
I won't try to speak for any "objective" standard here, I'm just saying the way I see it. Having a viewpoint about the Gaza flotilla protestors that is, to me, just objectively wrong, is okay. Telling another Lemmy commenter that they, the Lemmy commenter, should kill themselves is not. I can see how there could be debate about the first thing, but the second one is forbidden in practically every place on Lemmy that I know of.