This is an old charge, nothing will come of it. Im sure UFC higher-ups know and could care less. He was expecting probation, so Im sure they were too.
No biggie. He hit the cop without looking -- the cop grabbed him from behind while he was trying to break up a friend's fight. He swung before looking. Its not like he hit the officer on purpose.
EDIT: That being said, I still dont think pro fighters should be messing around with this stuff. But, some are still guys that drink... and that means fighting for no reason sometimes...