Fire situation on PAT

We had something in our scrimmage last week I wanted to throw out there. 

This is a varsity five-man mechanic situation.

On the PAT try, the snap is fumbled and the kick attempt is aborted.  The holder rolls out to the side that has been vacated by the Head Linesman because he is under the goal posts.  Who has goal-line responsibility?  Is the HL supposed to beat a 17 yr old kid to the corner or does the Umpire take responsibility?

 The referee should be wide and able to help support.  The umpire should also be wide to that side and help with the goal line. MHO