> This seems to be retribution, plain and simple.

It's hardly surprising as it's almost the defining feature of Trump - pettiness and revenge minded.

(though strangely, he hasn't publicly insulted his Pennsylvania would-be-assassin, but luckily his ear has healed remarkably well and so maybe he feels no need to do so)

When someone demonstrates actual power, he backs down and cowers. It's why he always ends up doing awkward submissive gestures when interacting with foreign autocrats. No real confidence, all bluster.