Boarding school isn’t relevant here. I honestly think you must let your son decide.
I keep thinking of the old folks’ story, which takes the general theme of “when I was your age, I had to walk to school in a snow storm…” Good for your son having to man up quickly and walk a mile to the store. I just don’t see that he deserves extra points for what he’s had to do, but perhaps I am cynical. If I were an AO, and I’m not, would I perhaps wonder what the goal would be of offering up these facts?
No idea what schools he is applying to, but he could perhaps make a nice supplemental essay from this circumstance.