His freedom of speech was not denied. A private venue choosing to not allow a musician to perform is perfectly acceptable. Citizens in Santa Cruz and Sacramento were exercising their right to free speech to voice their disaproval that a music venue would allow a bigot to perform.

It's a private group that wants to engender itself to the community it serves and profits from - I see no wrong done by either the Catalyst or the public.

Now, had Capleton attempted to perform, and he was prevented to do so forcefully by members of the community, that would be a violation of his 1st amendment rights.