Dan,
I hate to be cynical, but getting advice from Golf Magazine on this issue could be a bit jaded.
I played baseball from age 5 to 20, at every level other than pro. I picked up golf the week after I left my college team in the spring of 2001. I
STILL fight my baseball swing. Why? I still throw my hands to the ball when I'm trying to be athletic and I "forget" myself. What does that cause? Casting the club, hard.
Even when my timing is spot on and I lead with my shoulder turn but I leave a little of my weight on my back foot--a la the baseball swing--the shot moves left to right.
I also fundamentally disagree with Tom that in golf, your weight transfer isn't as marked. In golf--he's right--we don't step into the swing. But in baseball, 70% of my weight stayed on my back foot through the entre swing. It's just a agressive hip turn. My coach always called it "squashing the bug" with my back hip, leg and foot."
In the golf swing, weight starts relatively 50/50, then goes to the back foot--partially--in the backswing. Then, through aggressive shoulder turn--not hips--the weight moves laterally to the target and ends up almost entirely on the front foot. In my opinion, the swings could not be more divergent or counterintuitive when done side by side .
Hopefully your son is a better athlete than I was.