R.T.
As one of the few men here, I can speak to this. There is a lot of male image and pride in their "package." So, growing up, he'll just want to look as "normal" as possible. So, if he's have one normal scrotum and one shriveled, empty one, even if it is just for cosmetic sake, I'd consider it. And then later, when he can understand this more, you can explain. If it isn't prohibitively expensive, I'd do it. Medically speaking, I don't think he needs it.
Good luck,
Richard