Others might say he that as he remains President he has a duty to do whatever he sees is necessary for his country.
What is necessary is, of course, a matter of opinion but his may well be to protect the USA, and it’s allies from the worst excesses of someone regarded by him, and many others, as a totally unsuitable and corrupt felon who was the worst President in history, as best he can.
He could have just sat back and done nothing by taking the attitude that as the people put themselves in this situation then they should accept the consequences. It would have been a lot easier, but he took the more active path.
His country will eventually thank him.