It's not an ordinary case of free speech. This is a case of an extremist and 100% dishonest group causes violence, and deaths, with misinformation. You may as well say "let people make up their own minds" if I warn the fire department that someone is an active arsonist.
Also ROKU has established standards. The Burrow channel is in violation of them. Ipso facto, they should do something about it. Do standards mean nothing?