Free speech is good and must be protected, that's clear. But it should not be virtually limitless. The US played a major role sorting out the negative consequences of the Weimar republic, which did not contain fascist ideology, which then (edit: among other things ofc) lead to WW2.
It still baffles my mind how the US cannot see that tolerating the intolerant must inevitably lead to an intolerant and possibly facist society.