I don't mean to defend Trump, but my guess is his default position is to fight any resistance to him legally he can. He's the guy who responds to lawsuits to get him to pay his bills with countersuits, and looked for every unwritten rule and standard that was previously held only through an understanding of the norms and decorum and figured out every way to break or twist them he could. He has zero shame, doesn't care how he looks to those who aren't on his team, and would be willing to do this out of spite even if he had nothing to do with 1/6.