I myself have an allergy to mold (and most of the stuff that goes with it!), summers spent in my parents basement were horrible, even in some classrooms at school I was sick from it. Eventually, I've gotten more and more accustomed to moldy foods, though. (I suppose it could come from living in France, where people are much less worried with clean foods, the cheeses are virtually all moldy to some degree).
Depending on how allergic he is, it could actually be to his benefit to not try to hide from everything he's allergic to.. if he's okay eating cheeses with very little mold content (nothing visible, I'm not suggesting to go out and buy blue cheese or anything
), perhaps he'll build up a resistance naturally.. I'm quite thankful than I was able to.
Like chiggins said here, if children are *too* sheltered, they don't have the time to develop any resistance (I had the same problem, my parents were quite worried about me as a child, therefore I never really got resistance to some common things..)