While he was down on the ground, did Trump say, 'It's not that serious. Let me bleed for the camera'?
I believe we'd have heard him say that, if he had. We heard him asking them to bring his shoes. But when he didn't wipe the blood off his face, I was pretty sure he was waiting for the photographers who could grab some useful shots for the campaign.
Then up went his clenched fist, and my guess was confirmed.