I’m not sure that your dismissal is on solid footing. I mean, to be sure, the Trump legal team would try to make that argument but it misses quite a lot of points.
As your cite notes, we’re talking about two different things here: The FRA and the PRA. To my understanding, both have the same penalty but the rules on them are different. The FRA applies to materials created and owned by a Federal agency, while the PRA applies to materials created and owned by a small group near the President.
Many of the materials that the President would have tried to destroy would have fallen under the FRA. But under the law, the head of the agency is in charge of ensuring that the documents are preserved. As such, knowing that Trump would be liable to destroy a particular document, it’s quite likely that they would have ensured that there were other copies available.
The Executive Branch (and thereby the DOJ) is unlikely to make an argument that the President can’t override the agency heads about whether a document needs to be preserved, so don’t take the previous as an indication that I think that the President doesn’t have authority to destroy documents under the FRA, but: It’s doubtful that Trump explicitly stated, “Destroy this document and all copies.” In the majority of cases. And minus that sort of statement, it would have been completely up to the agency head whether he believed that Trump’s destruction of a document was just him venting frustration or an order to remove the material from the purview of the FRA.
In those cases where the agency head took an action to preserve a document, that would seem to indicate an intention to keep it around. Minus the President’s explicit statement to the contrary, in the historic record, it’s arguable that the archivist and the agency head could override the former President in saying that the document was intended to be preserved - especially if the new President indicates that the document is a material that is covered by the FRA.
A retroactive order to designate the document as “not covered by the FRA”, when you’ve left office and are no longer a President, isn’t terribly binding.
One might further note that many documents were collected and taped back together - presumably in Trump’s presence. The national press wrote about it, so it’s not like he would have an excuse to be ignorant of the fact.
That he would watch someone crawling around on the floor, gathering parts of a document, and not give them an order to make sure that it was not preserved would seem to indicate that he had no intention to remove the material from the record. Any argument that his action was an implicit command to destroy the record is disproved by his allowing the documents to be reconstructed. (Granted, that could also serve the former President as a legal defense.)
And, further, when it comes to the PRA, there’s a specific sequence of events is required for the President to designate a document to be not-suitable-for-preservation. Eating the document is not that. So, again, we end up with a situation where we have documents which were intentionally mauled and possibly destroyed, with good reason to believe that the President had no intention to designate the material as not-suitable-for-preservation.
Now, that all said, a principal component of a crime is the intention to commit a crime. And, of course, you have to ask whether a President can be accused of committing a crime while exercising (successfully or otherwise) the powers of his position?
For the latter of those two question, it’s a set deal that no representative of the people is authorized to corruptly use his powers. If the President shoots someone that he thinks is a terrorist - even though that person is an American citizen - the President might get away with murder, if it is believable that this was truly his agenda. On the other hand, if he murders a man that his wife was cheating with - no, that’s still a crime, regardless that it’s the President who did it. If the President pardons a murderer, who he doesn’t know and has no association with, he is simply doing his job. If, on the other hand, a wealthy patron gives the President money to get a pardon for a murder then that is corruption and the President would be guilty of Federal corruption crimes.
Fundamentally, the President has taken an Oath to execute the laws of the land, in service to the people. Using his powers and the law in service to himself is a violation of the Oath and he is left legally liable for any corrupt actions.
So the question purely comes down to whether he intended to commit a crime, when he was destroying those documents. If he was, for example, attempting to cover up another crime then that would be a fairly clear situation where he had criminal intent. And as such, he would be liable for the penalties of the crime.