Being just about as old as that old man, and being stronger, and better with balance than he (based on how he fell), i would guess that he wouldn't want to risk even a planned fall, because if he'd have landed with a certain amount of force on the wrong part of his head, he could have died. It didn't look even remotely like he deliberately let himself fall. No 75-year-old that I know would deliberately fall backwards onto cement or concrete in order to "get a policeman into trouble", or, for that matter, for any other reason. And he's tall, too. His head had a long way to come down. If he had fallen backwards on purpose, he'd have instinctively tried to cushion the fall with some twist and attempt to brace himself, or avoid hitting his head straight on. Saying he did that on purpose is ludicrous.