T.H.
Yeah…school was partially my concern, among other things. I think at 6 he needs to do it. My son had no interest in doing it himself either but I did force the issue. He's 5, almost 6, and if I would he would totally still want me to do it. He would also complain about how yucky it is, etc. but I explained that it's also yucky for me to do it, and that everyone has to do their own bottom, it's not like we're all getting out of it and it's only him.
There was a time when my son just decided he'd skip it (and show me!) but then his underwear would get messy and so he'd have to wash it out in the toilet. I didn't get mad or anything, just stand there and make him do it til it was mostly clean. He didn't love that either, so he started wiping, or at least trying a lot harder!
This is a bit of a stereotype, but I do think boys are more prone to standing back and letting mommy handle everything. My son doesn't really like doing anything for himself and would prefer me to do it all…so would my husband if we're being honest.
Bottom line (haha, pun intended!) is that it's time. He needs to learn. He can do it. It might be messy but it's part of life!