They could ban booters. But then someone else will say "but you allow <some other type of site>! They're clearly bad, you should ban them too". And so they do, and now someone else complains about some other site. Once you start banning sites for the content they hold, where do you draw the line? I don't fault CloudFlare for drawing it at the legal barrier (e.g. no CP).
CloudFlare should not align itself with the adversaries its mission is to protect its users from. This isn't a slippery slope distinction, this is a binary exclusion.
You can say that. But I guarantee you if they do that, other people will think they should ban other sites too.
Really the only way to avoid the problem is to not play the game, and so that's what CloudFlare does. It's pretty much the only defensible stance to take.
