I have a hard time getting upset about this, as I often ride my bike places I'm not supposed to (allegedly). A couple of people doing it probably isn't a big deal, but if they all start telling their friends then it could become a real problem. I also wonder if it was moto riders that cut out that tree on Oreland.
I was there on Monday and I was just behind a moto. I heard him but never saw him. The one thing I could say is that this guy actually had decent throttle control. I could see some spots there the tires dug in but mostly not. I was still curious to see if I could find him and see who it was or what bike they were on.