But he declassified them, so, he doesn’t have any classified documents at his house.
A properly crafted subpoena would allow for that response. Your statement would serve as an objection in a series of objections. Unfortunately, objections do not relieve one from providing the documents. The ways to quash or modify a criminal subpoena is claiming that the subpoena is unreasonable or oppressive. (Fed Rule Crim Pro 17(c)(2)). The odds of prevailing in general are slim. With this judge, nil.