The Umpire in this situation.
From CCA mechanics manual 7 man crew.
Goal Line Positioning and Zones
Umpire: Starting position needn’t be as deep as scrimmage plays but don’t block goal line for wing officials. When the ball is snapped on or inside Team B’s seven yardline and no alternate official is available, you are primarily responsible for the line of scrimmage in determining if the passer was beyond the line of scrimmage and if the pass is beyond the line of scrimmage.