I believe any good reliable handgun is a LOT better than no gun if he needs one in a hurry outside the home. Even a 22 is WAY better than his bare hands.
So it's a matter of what kind of handgun he can manage and what he WILL carry on his person. It the gun is too big or too heavy he will leave it at home or in the car.
If he is not going to carry the gun on his person then he should not get a handgun at all. Get a carbine of some sort. Or if recoil is not a problem, get a shotgun.
AK 47s are very useful. Heck, even 8 year old Vietnamese girls could handle them well. They are super reliable and not too pricey.
ALWAYS use a long arm if you can. Handguns are the best weapon for anyone to buy if they intend to be armed and STAY armed all the time, because you can't schedule a life threatening emergency.
But if carry is not going to taken seriously I say again, get a rifle, carbine or shotgun.
Facing an old man with a cool head in a life and death fight; if that man was even armed with a Ruger 10/22 would not be a good plan for any young punk.
Hits count. Misses don't. Ease of hitting is important.