I shoot right (skating "out") and catch left. It's been a real battle for me to learn to stick-handle, but over time it came to me. It takes a lot of dedication and practice, and I've learned to "know myself" and my limitations. Sometimes I do a "proper" clear, sometimes a backhand swipe (mostly along the boards to my right) and on occasion, when I have time, I switch hands--but I do this rarely, because I hate for the other team to see it. They know then that they can pressure me when I stick-handle.
Over time I've come to accept that I'll never be a great stick-handler. It's a sick joke because I grew up idolizing Mike Richter.
I still make mistakes frequently, because I just don't have the feel for the stick that others do. So I play careful, don't take chances with the puck, and I always hang close to my crease in case I commit (horror of horrors) a turnover. That way I can reset myself and make the save as I normally would.
Man, am I longwinded. Bottom line: If I were you, I'd have your son practice, practice, practice with his stickhandling--the way goalies are "supposed to," because that's the fastest thing. And I'd reassure him that not every goalie has to be a Hextall, Brodeur or Barasso. Look at guys like Roy, Richter, Dafoe--even Hasek can't handle the puck well, All-Star game notwithstanding.
Teach your son to be a safe puckhandler rather than a fancy one, and focus more on making saves than on making pretty passes.
And don't ever encourage him to be like Joseph--teams that pressure him when he has the puck get easy goals. His technique IS inferior.
Chris