Who seals the move at adjournment?

According to the Championship rules:

After 4 hours of play, White will make the sealed move when the TD indicates it. 18A ... "If the player who is told to adjourn makes a move on the chessboard, for whatever reason, that move becomes the sealed move and cannot be changed." From the U.S. Chess Federation's Official Rules of Chess.

While this rule eliminates any uncertainty regarding who is to seal, I've always thought that it created another potential problem. What if Black is on move when the TD indicates that it is time to seal and Black has already completed the first time control? He could ponder his next move for almost an hour (or possibly more) before White has an opportunity to seal. Therefore, a playing session intended to end just after 11 pm could extend past midnight.