Or it could all be something as simple as someone at the National Archives got antsy about the safety of national documents required to be preserved, especially with archivists no longer attached to the former President to scotch tape together documents he had a habit of destroying when he was done with them, in spite of numerous requests not to do so while he was in office, thought seizing the documents when he was away for the season would draw little attention, enlisted the aid of another federal agency to make the seizure, and now we have this kerfuffle. Never underestimate the power of sheer stupidity and ignorance.
(Of course no one would accept this explanation. Pundits on the left desperately want to feel like they finally "got him," and pundits on the right want to continue feeding the outrage that fuels their bottom line.)