You won't have anything to worry about with the WG models, as far as durability goes. One thing that I noticed I did not like about them, and what the in-depth review here on PF also points out, is that the shutter button is a bit hard to push, probably because of the heavy waterproofing. Not sure if it will be harder for him to push due to having a weaker hand, or possibly easier since his finger is a little smaller and maybe he can concentrate the pressure better, where it matters.
I guess if it turns out to be a problem for him, then you can keep it for yourself and get him something else.