There’s no such thing as “So hateful it’s harmful”, that is a facade or a tool of deception used to censor someone because the other side can’t prove it to be false.
You cherry-picked the comment you quoted, leaving out important context: "Their view is so hateful that even giving a platform by engaging with it can be harmful." My reading of this point is that giving a hateful idea a platform to spread is a reason to disengage with it, because by engaging with it you are giving validity to it in the mind of the author of that idea.
Even so, this is such a strange statement for you to make. So strange that I simply have to ask further: How do you reconcile this idea of yours with both the continued existence of antisemitism online, and being the mod for the !judaism@lemmy.ca community? Don't you see antisemitism as a hateful set of beliefs that should be eliminated? That it should not be given a platform to spread? Of course, by your definition that would be "censorship".