If he plans to go to the range regularly, he should get a pistol that uses a cartridge he can afford to buy. If he plans to carry it, 9mm (35cal) would be my suggestion for a first carry/range pistol. I have seen more than a few new gun owners buy 1911s thinking they are the only thing to own, then turn around and sell them for a loss when they realize the ammo is too expensive.
If he doesn't plan to visit the range, then whatever caliber he is comfortable with from his service, as it will be more effective for self defense in the shortest adjustment time.
And a last suggestion, give him the money and let him buy it himself. You will avoid any chance of hassle from a perceived "straw purchase", and he will get the chance to pick one that fits him best.