Interesting thread.
Having been deep in running "crew culture" for about a decade, I can tell you that this (mostly white) groups are absolutely crazy about cheer-zone/beer-zones, aggressive high-fives whether you want it or not, etc etc. Don't know if I've ever seen a confetti cannon, but it sounds like it would fit in with the antics crews have been bringing for years.
In all these years and dozens of large races partying with crews, I have NEVER seen police get involved, ever, and I sure as heck haven't seen a situation that couldn't be been handled with a few friendly words from officials (or neighboring fans) to the ultra-enthusiastic hardcore crew people.
Let's be honest: black people are more likely to have the cops called on them, and if called cops are more likely to have an over-the-top response to black people. Everyone knows this. Remember that Central Park dog park lady? There's a reason she immediately specified that a black man was bothering her.
I find it really funny when people deny this. I'm a pretty light mixed person, and every weekend I see the difference between hanging out with white friends and black friends in public. With a mostly-white group we can be as loud as we want and pretty much do whatever, whereas with a mostly-black group in the same city people are immediately unpleasant to us even if we're not loud. (And yes the cops are MUCH more likely to somehow come poking around a black barbeque, ha!)
