I don't know that it was politically motivated at all...though it seems like it should be, as you are noting....
There are a good chunk of Republicans who are Republican, but NOT Trumpers....
Maybe his parents were Trumpers and he wanted to hurt them on his way out the door with his suicide by cop plan, maybe he was a Manchurian Candidate? Maybe he wanted to impress a girl or guys on his gun and demolition site.....maybe he was a pawn working for someone else
Even if he had this uncontrollable hatred towards Trump, was it worth his own life for it? He HAD TO KNOW he would be killed... This is someone with mental issues, how could it not be?
Normal people who hate Trump or hate Biden or hate Obama or hate Bush, don't go out and try to assassinate them.
the whole thing is really disturbing to me, because we DON'T really know yet, why he would do such an evil thing? What triggered it?