I'm not sure why you see it as a single incident. It was a series of choices—actions—that outline his overall behavior. I don't see how a person who shows no empathy towards others, particularly from a position of 'power' over them, then refuses to acknowledge their poor behavior should get any empathy themselves.

It has always been a very easy option, if he wanted, to ameliorate the situation himself. Instead he chose to stick to his choices multiple times.

You're not wrong that it could be considered taking the high road to never bring it up. However, too often do people abuse that expectation to avoid consequences and just continue their behaviors. Without acknowledging their own actions there is no evidence that this is just not their own standard of behavior.