Maybe because he's been impeached a couple of times, the witch hunts have never stopped, and it looks like once he gives up any documents showing proper intent on something anyone considers questionable, he's screwed? Documents can prove multiple things like correct intent, proper action, correct situational analysis, and (especially in DC) what facts were provided as the basis for a decision. Who is to say that once turned over Trump could retrieve the documents if needed for his defense? If you are saying that Trump shouldn't have the records to document his administration (and I won't completely disagree), then all the presidential libraries should be closed and presidential memoirs zapped (footnotes, etc). In other words, thanks for your service, out the door, you are nobody special from this day forward ... and you really think a narcissist (and all politicians are) can accept that?
If you can show the classified documents were classified by an intelligence agency or the military to protect real secrets rather than inconvenient political actions, then we could probably find some common ground ... but those things are more commonly leaked by an E3 Nobody who shouldn't have had access in the first place.