You sound like an expert. There was no sound, how do you know if, when his hands came down he wasn't responding to being shot to begin with? Or was he shot when the police initially fired on the truck at the first stop. You are speculating on things you have no idea about. How do you know the police didn't have a throw down gun for him? You don't know nearly what you think you know.
I'm betting you don't "know" any more than anyone else who wasn't directly involved
This guy has some logical ideas on the subject and shows supporting facts:
http://bearingarms.com/lavoy-finicum-murdered-forced-oregon-police-shoot/