Innocent until proven guilty beyond a reasonable doubt applies to the police as much as it does suspected criminals. The irony is that the live-streamed video possibly helped the officers defence by showing him live saying that he thought the guy was going for his gun (not concocting that story after the fact).
Right. The cop default excuse: "I thought he had a gun!" The magic get-out-of-jail-card and the best, it always works!
When the stars threw down their spears
And watered heaven with their tears:
Did he smile his work to see?
Did he who made the lamb make thee?