The arguments presented here in defense of Trump are all wrong
It doesn't matter when the docs showed up at Mar a Lago (though I suspect all or at least a large majority arrived AFTER he was no longer POTUS) and it doesn't matter if they were declassified or not (and of course there is no evidence that they were declassified since that is a process that involves other groups and isn't just by the POTUS "thinking" about it)
None of that matters
The documents are GOVERNMENT PROPERTY and they don't belong to private citizen Trump
The government informed Trump they were missing and he failed to return all the documents and even after a subpoena was issued he continued to retain documents and LIED about it which is obstruction.
That's the bottom line. This is government property and he knowingly retained them and LIED about it.
That is why he's facing legal jeopardy. The obstruction and lying and failure to return docs that he's been informed don't belong to him is the issue.
He was also informed by his former attorney of the legal consequences of retaining documents that didn't belong to him, both classified and unclassified.
None of them belong to him
A former White House lawyer for former President Trump warned him last year that he could face legal consequences for holding on to presidential records, The New York Times reported on Monday.
Eric Herschmann told the former president in a late 2021 meeting that he could face investigations and legal repercussions if he did not return government materials, particularly classified documents, according to the Times. Herschmann was not working for or with Trump at the time, the newspaper noted.
https://thehill.com/blogs/blog-briefing-room/3651609-former-white-house-lawyer-warned-trump-last-year-about-legal-risk-of-mar-a-lago-documents-report/If he had just turned over all documents when first asked and fully cooperated we wouldn't even be talking about this today