If we all look back to our younger days, I think we can see a much more plausible explanation for their actions. Hell raising.
For certain people at certain ages, it's FUN to riot, throw things at the cops, trash stores, overturn cars and burn stuff. It is exactly the real lack of coherent messages from the "protestors" that supports this obvious conclusion. At the University of Michigan, the riots were basically the same, only the justification was more banal--the outlawing of booze on campus.
It should be obvious that these riots are not so much ideologically motivated (though that's the pseudo-rational), but testosterone motivated. Most of these monkeys couldn't spell anarchy let alone understand it philosophically. Let's not confuse the cover story with the real motive--fucking stuff up for the fun of it.
And so you propose that the protestors travelled hundreds of miles, putting themselves in direct danger of physical harm, simply for fun? Certainly the UofM riots don't illustrate that mindset... I would submit that you have no idea what the protestors actual motivations are.