Blaming another party for a crime is a common tactic for a defendant. The idea, obviously, is to hopefully instill reasonable doubt. Sometimes the claim is even true, most times it isn't. It's up to the prosecutor to convince a jury otherwise. I'm not a lawyer, but I can think of no reason why a judge would deny this defense tactic. And this is coming from a guy who does not like the defendant.
Now, as far as irrelevant statements about drooling Joe, I can understand the desire to prevent campaigning from the courtroom.
It's irrelevant. Trump was not afforded due process. There is no rational discussion, it was the definition of denial of due process. If you know what that means, you cannot disagree, it's not in question. Trump was given no chance to defend himself against a panel of seven Democrats and it was still 4-3, MAGA man