It is unfortunate but Trump is only human. He gets nonstop 24/7 TDS thrown at him. Much, much, much more than any of us. It would be easy for anyone, right or left, with that kind of nonstop hate coming at you to slip up from time to time. He's done an exceptional job dealing with it most of the time.
I am not excusing what he said. I'm just glad I am not in his position. I don't know if I could handle that kind of pressure along with the pressure of being the president. Most presidents go into office looking fresh and come out looking like an old man. It happened to Obama and Clinton. Biden didn't look any different because he was too senile for the pressure to get to him. He didn't know where he was or that he was the president most of the time. Trump has held up the best for someone who is so much on top of things.