Earlier quoted context omitted.
Interesting. This is the first I have heard of this and CloudFlare's reputation has just gone up my eyes because of it. Is ISIS dangerous and deplorable? Sure. Are there ideas so dangerous that they do not deserve to be exposed to public discourse and judged on their merits? I don't think so.
I don't follow; CloudFlare is not the government, therefore freedom of expression isn't really the issue here. Who they choose to give a voice to says a lot about them. I would oppose the government censoring ISIS; however, I would be proud of any company that refused to to business with them.
I don't think they're choosing to give anyone specific a voice. I think they're choosing not to make judgement calls.
Once you start blocking anyone, you've weakened your ability to refuse to block others. You'd see greater demands for blocking Wikileaks, censoring articles like https://en.wikipedia.org/wiki/Illegal_prime, enforcing Europe's right-to-be-forgotten, etc. on the basis of "well you were willing to block ISIS".