it's their speech advocating for depriving others of their speech specifically.

And is that speech destroying freedom of speech, or is it their ensuing actions?

but when someone goes around demanding others be silenced for words they say and then gets hoist by their own petard? sorry, I'm not gonna actively try to get them banned, but I'm not gonna waste time trying to get them unbanned, either...

Sure, I can agree with that. I'm not going to shed a tear or waste too much energy on them. But I wouldn't cheer it on, nor advocate for such situations either. A dose of their own medicine is funny, but it's not a principle I'd uphold.