I think I can shed a little light on this....
From my perspective, I saw this coming before the cops even came out. The problem was what in WA we would call disorderly conduct. When a person intentionally disrupts a lawful assembly. Dude was chiming in when douche guy was speaking. Remember the old addage "I don't agree with what you say but I'll defend to the death your right to say it!" Well....that's what's going on.
This guy wasn't arrested for touching the cop, he was arrested for disrupting the assembly. probably would have gotten a ticket and released after the rally but thats usually something you take people in custody for....becuase if you don't problems continue.
Now, once he's been advised he's under arrest, he chose not to comply. he's a big dude and pulling away from the cop trying to put on the second set of handcuffs (becuase they're trying not to be dicks) isn't wise. He'd already made his point, resisting is just another charge he's got to deal with and it's not like he was going to be getting away.
I thought the cops were within use of force guidlines. they even appeared to be trying to be cool about stuff, guy wasn't immediately dumped when he started touching cops, they just pulled his hands behind his back. Moved him to the side, tried to talk to him about why they were doing what they were doing and put on a second set of cuffs for his comfort.....
And, this was an anti-gun rally they were protesting. Imagine this WAS a pro-gun rally and a bunch of hippies showed up and began interfering with your speakers? wouldn't you want them arrested for ******* up your show?
Constitution protects everyone, not just those whose message we agree with.