Nobody else I can find is really pointing it out, but the president has much more of a pass than you think on this one.
In fact, Robert F. Turner, associate director of the University of Virginia's Center for National Security Law, said that "if Congress were to enact a statute seeking to limit the president’s authority to classify or declassify national security information, or to prohibit him from sharing certain kinds of information with Russia, it would raise serious separation of powers constitutional issues."
The official documents governing classification and declassification stem from executive orders. But even these executive orders aren’t necessarily binding on the president. The president is not "obliged to follow any procedures other than those that he himself has prescribed," Aftergood said. "And he can change those."
The fact is perhaps missed in the fire that's currently ensuing right now, but the reason this is a big deal is because the president can't declassify things that are classified by statute (since the legislative branch made the decision to classify them, not the executive branch). Nuclear documents are the prime example of that