https://storage.courtlistener.com/recap/gov.uscourts.flsd.618763/gov.uscourts.flsd.618763.58.0_1.pdfFull text of Trump lawyer's retort
its quite a long read
but in particular, it draws attention to executive order 13489, issued by barack obama the day he took office, which explicitly says that former presidents may assert executive privilege in connection with the release of Presidential records by the National Archives and Records Administration (NARA) pursuant to the Presidential Records Act of 1978
https://obamawhitehouse.archives.gov/the-press-office/presidential-recordsthat's kind of hard to argue with when it comes with Trump's ability to assert executive privilege for his documents, as a former president, nevermind the claims of a standing order of declassification
since that order was never revoked by any president since, its law of the land.
most of it goes into tearing down the arguments by the DoJ. Saying that by claiming that the existence of potential classified documents negates standing, regardless of whether they actually are classified as a matter of law or whether they constitute the whole of the search, would set a precedent where courts could have not only their entire mechanism of relief but even standing for judicial review, effectively nullifying the fourth amendment. Any prosecutor could just make any claim of illegally possessed documents in any search by inverting the precedent in Wong Sun and saying that potential possession of illegal materials negates standing for claims of wrongful search.
His own attorneys never substantiated the declass claim in any of their court filings. It was never mentioned, not once.