The press made specific accusations that Trump had classified documents at his residence. It was part of the what the DOJ said they were investigating. Part of the justification of the raid was to look for classified documents. It's a relevant part of the conversation and not a red herring. The red herring is a belief that the president could not have those classified documents, solely because they were classified.And again I am going to ignore your red herring.
The case against him doesn‘t hinge on whether or not the materials were classified at all, it centers on whether or not he was authorized to possess official materials privately (even while in office), and whether or not he has any right to retain them upon leaving office.
So far the courts have sided against Trump at every turn on this one, so I’m not sure why you think you have the high ground here.
However, the records retention act is a relevant part of the discussion because that's really the only legitimate law that may have been broken. And that part of the case is a sticky wicket for Trump. But, it did not rise to the level of a DOJ raid unless you have a specific bias that requires Trump always to be in the wrong, regardless of facts.
The records office was aware of the documents. Trump was working with them, though, perhaps it should not have been as much a negotiation as it turned out to be. This looks more like Democrats needed some dirt so they used this as a way to justify raiding his home to get it. The courts would have been a more appropriate place for the archive apparatus to resolve any disputes over which documents were subject to the archive act. It did not require a DOJ raid.