Perhaps, but I think it’s often less a matter of being afraid of calling extremists out, and more of what I heard someone once refer to as “sane-washing”. Progressives hear extremist views and say “when they say X, what they really are saying is Y. No one actually wants X”, when in reality that’s exactly what extremists want and it gives them cover to continue to push the Overton window until it’s no longer an extremist view. The above exchange is a perfect example.