Bob Mueller was clearly senile when he appeared before Congress in July 2019 to explain how he came up with bupkis after a 2-year investigation into alleged Russian collusion. It was apparent that other members of his Special Counsel staff were calling the shots and Mueller was their sock-puppet. I didn't dislike the guy, I just felt sorry for him. Had he been in full control of his faculties, my expectations would have been higher. I would have expected him to come clean and say - sorry, but there is no there, there.
That said, Trump is a major league jackass for saying I'm glad he's dead. Trump was also a jackass when he said the same thing about Rob Reiner. What useful purpose was served by those Truth Social posts, other than proving Trump is a major league jackass? There is a time to fight, fight, fight and a time to stfu and let the dead RIP.