I guess that might be something to worry about if it starts to happen. But I think it's a pretty poor argument to say "well if they ban racism, what's next?"
A lot of people in this thread are mentioning the default subs - how is a mod of a sub with 8 million subscribers supposed to make sure every single thing posted isn't 'offensive'?
It's an odd hodgepodge. Another reason why it is probably worrying people more than it probably should.