How can this gentleman be briefed on security issues? How can he count, or be told, the number of rows to an exit? Would he be able to use the O2 masks if they were deployed. How can he follow the instructions if a crew member in an emergency?
How would the crew communicate with him?
I think, in this case, it was appropriate that he have a travel companion.
Apparently U2 has already offered him, and a companion, free tickets in addition to a full refund for his original ticket.