The President shouldn't ever be charged with mishandling classified material. Period. The President can declassify or classify the material whenever he wants.

You bring up an interesting point about the authority of the President to declassify information. Historically, this power has been used judiciously, such as when President Kennedy declassified information during the Cuban Missile Crisis to inform the public about the situation. However, if this power is misused, it could potentially put national security at risk. Where should we draw the line to balance the need for transparency with the need for security?