@ simplechamp
one main difference. bmx bikes would trash up the rc track designed for ~10lb cars, while the skatepark would not be harmed by a ~10lb car, compared to, say a 200lb skater. and I don't think the skaters are pissed for "the safety, seeing as a bunch that I see dont even wear helmets.
If they do, then they're nice and safe from falling R/C cars so they got nothin to worry about!"
but then again, who is to say they own the park? You are not doing anything illegal. just be smart and keep your distance. from em. if they're on the half pipe, stick to the funboxes etc. If they still make a big deal, well my friend... that could be classified as harassment.