Because telling/asking him to turn his music down worked out so well for them...They didn't say he couldn't be there, just didn't want him to impede/interfere with an active armed robbery situation.
Looking at his history, my snap internet judgement is that they guy is a crusader. Someone who's had as many run-ins with the law as he has claimed to have had, should be looking to stay off their radar...not roll up to a perimeter with music blarring and prowling around the scene with a huge dog and a video camera.
I believe he went there specifically intending to instigate a law enforcement response against himself, hoping that things would go south and he could get another payday from the city. He got what he wanted. He'll probably get his payday at the expense of his dog, some real "innocent bystanders" who had to witness the shooting, and a couple of cops who will have to deal with the fall out....and we'll hear about him in a few years dying of an overdose, beating up a hooker, or committing some other thug life crime.
