Francis, you are over-analyzing again. Just have your son contact the schools he is interested in directly. The likelihood of any meaningful action based on the school or schools one listed on their PG profile are rather slim, I'd say. This is another one of those things that isn't really worth putting much head space into.
A school would most likely have to have some interest before checking a player profile. If they have interest and the player has done his job and contacted the school he is interested in up front, this becomes a mute point (except maybe a subsequent feel-good point "hey, look he did list us").
I suppose one could argue that a school may do a search for players who have interest in their program. But big schools and/or strong programs are not going to look for players this way - perhaps use for tertiary cross-reference at best. And, again, if the player has interest in other schools, he should have contacted them directly along with viable references to begin with.
And on the other side of the coin, if a school likes a player, they aren't going to kick him off their board because he listed a bunch of other schools on his PG profile.