Probably for the same reason they ban people. Twitter reserves the right to do whatever the fuck they want with Twitter accounts, which they own. If they want to ban an account, they can do that without any reason whatsoever. If they do not want to ban an account, they can refuse to do so without any reason whatsoever.
That's all there is to it.
His presence there is a yuge form of advertising for twitter. They're not going to want to walk away from that (in fact, it wouldn't surprise me to find that he gets paid to post there)
MMO champion reserves the right to do whatever the fuck they want with their forums just like Twitter reserves the right to do whatever the fuck they want with Twitter accounts. You can complain about it, you can call them hypocrites, but it's still their right. Let's not forget that freedom is still freedom even when you disagree with it.
Also Twitter doesnt ban hate speech.
He's a walking advertisement for it, why the hell would they ban him.
The Fresh Prince of Baudelaire
Banned at least 10 times. Don't give a fuck, going to keep saying what I want how I want to.
Eat meat. Drink water. Do cardio and burpees. The good life.