Granted that as a scientist Dawkins should not get carried away with his emotions and make really dumb unscientific pronouncements about Islam but pointing them out should be sufficient remedy without attacking free speech rights.
Examples: Nobody calling himself a "rationalist" would make this stupid Dawkins tweet: "I think Islam is the greatest force for evil in the world today. I've said so, often and loudly." There is no such thing "Islam" tout court -- there are Sunni's, and Shites, and Alawites, and Sufi's, etc., and many permutations of all the above -- saints and sinners just like any other group of humans. Such a general tweet is just foolish ("evil" isn't even a useful term for a rationalist).
" In 2015, he wondered whether Ahmed Mohamed — the boy in Texas who was suspended after bringing a homemade clock to school that officials said resembled a bomb — wanted to get arrested given that the episode led to an invitation to the White House and crowdfunding." Dawkins must think the young man has prescience.
Just like the rest of us Dawkins says stupid things and doesn't always let logic and science overrule his emotions. As a "passionate rationalist" we can hope he will be more rational and less passionate but even if he isn't he shouldn't be censored and have his talks canceled by hypocrites.