"The Main Casualty Of The Cancelled Trump Rally Is The Idea Of Free Speech"

   I think this is basically right.
   Trump's buffoonery does not excuse the liberal/leftist protesters for shutting down a political rally. Has trump incited violence? Then he should be charged with inciting violence. If not, then he gets to speak.
   In general, I think that a lot of unfair charges are being directed at Trump. This is possible because the left and the right admit that he needs to go: the left hates him with a seething passion, and the GOP establishment doesn't want to lose control of the party. IMO he doesn't really mean anything he says. He's a bullshitter; he just says things. There's no real there there. Trying to make him out to be Hitleresque is unfair, false and stupid.
   The protesters interfered with Trump and his supporters' rights to speak freely and assemble. That's bad enough as it is, but it's particularly worrisome against the background of these things:
(a) The PC left tends to reject the very ideas that freedom of speech is a right and a good.
(b) Liberals tend to protect and enable the PC left and its actions
(c) Trump is the very kind of guy--and disrupting his rally is the very kind of thing--that tends to drag more  liberals in the direction of the PC left.
   Make no mistake about it, what we've got here are two threats to liberalism, not one threat and one defense.