Eventually when he gets tired of it or just wants a change, that LH rifle will be nearly impossible to sell and its value will be next to nothing. Get a RH rifle and learn to use that. It is a right handed world .... adapt and overcome.
You might want to check your facts on that... been a lefty all my life and am what some would call a 'gun slut'. I've bought and sold many dozens of lh rifles over the years and have never had trouble moving one for a fair price. I find more every week and have to look away either because I don't have room in my safes or I'm just not interested. I know many others in the lh fraternity in the same sitch...
Hell, I even have a lh Ruger .375 in SS laminate...a factory built rifle not even produced for righties lol.
Lefties rule! Righties drool...