“So why not sue on the basis that many of these instances involved provably true statements by Trump; thus the claim that they were disinformation has defamed him.”
That’s not enough grounds for a suit even, since he is a public figure. He would have to show demonstrable harm as well, and possibly malicious intent too.
A good example of that is the Johnny Depp case, in which he is likely to win because he can demonstrate that he lost a multi-million dollar film contract directly because of the defamation. Trump might be able to make a case that they hurt his reelection chances, but the courts are going to want to see monetary harm, which I don’t think that would satisfy.
What about people who voted for Trump and now pay exorbitant energy bills ? That is directly attributed to the election of burden.