He is right hand dominant. When he switches to hit left handed, the immediate area of strength is going to be power because his strong right hand becomes his pull hand. I would venture to bet that he also pulled more balls than usual. Not at all uncommon but not a reason to switch. As he grows in size and strength, he will develop power from the right side while maintaining all the other benefits. RJM lists several strong reasons not to switch.
Cabbage, I hate to disagree with you, but the top hand is the power hand, correct? At least that is what Ted Williams used to say -- I thought I remembered that so I just googled it and found this: www.nytimes.com/2002/07/06/spo....400-dies-at-83.html
"A natural right-hander who happened to bat left-handed out of his 6-foot-3-inch frame because that was the way he started swinging when he first picked up a bat, Williams threw and did everything else right-handed. He said batting wrong-handed cost him power because it was the top hand on the bat, the one nearest the impact with the ball (in his case, his weaker left hand), that provided a swing its power."
P.S. -- I don't disagree with your advice not to switch, BTW.