There are other ways to obtain the information. The court could issue a subpoena to the business asking for the records. There is no issue of executive privilege since the records would be from the business not Trump as President. They could also a write to all guests of the hotel informing them about the law suit and legal issues. The letter could ask them.to confirm their stay and whether they have ties to foreign governments. They could at least start with the foreign delegations at Mar a Lago for meetings.