I don’t even see how his reaction was a “typical authoritarian response”. I think there are only a few reasonable responses after being shot. Defiance is a pretty reasonable response. Anger, fear, running away, and mental breakdown are all also reasonable responses.
I detest Trump, but his immediate reaction actually seemed like the best reaction that a presidential candidate could have. I don’t think it was planned and I do think that his reaction was genuine. I think it’s very hard to have a calculated response in a situation like that.