Lot’s of places on this planet have hyper radicalized portions of their populations that commit aggregious acts of violence, and they lack free speech.
Yet free speech is being used as the red herring to blame.
Unequivocally, your assessment of these forums causing the radicalization is wrong. Plain wrong. These people exist in any environment, they go into the shadows, they continue to lash out, and removing and restricting rights for every person DOES NOT STOP THIS BEHAVIOR.