Agreed. If he had chosen to surrender to the cops, like they asked him too, instead of choosing to go out in a blaze of "glory", he would have been taken before a judge, charged, and prosecuted.
The judge, after all wasn't at the shootings. He has to listen to the lawyers and the testimony and determine what happened. And once this mug made it into the court system, he would be considered to be innocent until proven guilty.
But first he has to surrender, because if he chooses to continue the firefight, he will lose. As long as he's an an active shooter, he is a threat to the public and to the officers trying to arrest him.
He decided to turn this into a "shoot to kill" situation, not the cops. The cops decided they'd rather send a robot than waste any more LEO lives. At that point, his life was pretty much forfeit.
And if it took the cops 20 minutes to make the decision, I bet 19 of those minutes were taken up by the cops arguing over who was going to get to and drive the drone, and another minute of "rock, paper, scisssors" to decide.
Don't forget at least three minutes to eat the Whoppers so the bag was empty.