As far as I can tell, /r/antiwork doesn't equate having a boss with slavery - they say having a shit job with a shit boss is a shitty situation they should not have to put up with. And, frankly, that seems reasonable.
I have no idea about the other subreddit you mentioned, but it does sound superficially like a spot racists would meet up. But it's been banned so I'm just judging it by its title.