He went to the store, high on fentanyl and meth.
He paid for cigarettes with a counterfeit $20 bill.
Store clerk took the bill, but realized it was fake as he was leaving.
Store clerk went outside, saw Floyd sitting on his car, asked for the cigarettes back
Store clerk went back inside, called the cops.
How it escalated from there is unclear, but Floyd was high, acting strangely(clerk thought he was drunk), and refusing to cooperate with the store he had just cheated. Do you think he was polite and cooperative with the authorities who showed up to make him give the cigarettes back? If the police had just snatched the cigarettes from him, what would stop him from drawing a weapon or fighting back in some way? Procedure was to arrest, aka physically restrain, for the safety of all involved.
Once physically restrained by the police, do you think he sat there and took it? Do you think he, in his altered mental state, laid there breathing calmly, or is it more likely that he was agitated by the series of events that he forced to happen(by refusing to give the cigarettes back to the clerk when asked, more so than paying with a $20 that he may or may not have known was fake)? Now the cops have Floyd upset and handcuffed. Should they let him run around like that? Should they ignore procedure(full process and documentation of the crime and arrest) and let him go free? What they did was restrain him, using a method they were taught and allowed to use. They recognized that he was under the influence of something. They recognized that his health was in jeopardy. They called an ambulance. They followed procedure at every step.
George Floyd wasn't executed. He wasn't given the death sentence for his crimes. He ODed on drugs he took of his own volition while being arrested for a crime he committed.