This is something I'd definately go along with how difficult child feels about it. 13 is an awkward age at best. No need to make it worse with the potential for severe peer teasing if he's seen. Especially if it's not really something he wants to do.
Travis wanted to see Santa at 13, we didn't get pics, and he used Nichole as an excuse, although he really did want to see him. Travis still believed in Santa clear up til I think he was 16 and I finally just had to tell him otherwise. (took alot of convincing too)
However at 13 Travis' "developmental" age was at about 5 yrs.
Hugs