What will he be using it for?
I'm a big fan of the .22 Hornet, and it seems like ammo availability for it is surging back in the last few years (compared to say 5-10yrs ago). Or maybe I just complained enough at my local shops and they started stocking more for me...
For deer, it's a super-specialty rifle. It's not too far off of a short barreled .223rem, and yes, it will kill a deer, but no, I wouldn't say it's a deer rifle. Guys use them, and I wouldn't hesitate to take one out, but I'd acknowledge that I'd be passing on a LOT of easy shots.
For coyotes, it's a short range proposition. A little more pop that a .22WMR, but again, not as much as a .223rem. I limit my shots basically the same for a .22WMR and a .22H, maybe a little longer for the hornet (100-150max for the .22WMR, 150-200max for the hornet), but I can depend on better killing power out of the .22H.
Bobcats and Fox are the reason I own a .22H. Fantastic round for these predators. Enough stuff to reach out and deliver fast kills, but gentle enough to save me a lot of needle time, and helps avoid ruining a $150-200+ cat.
For small game, squirrels, rabbits, crows, etc, it's a little expensive compared to a .22lr or .22WMR, but it's fantastic in the field. If you don't mind the ammo cost (compared to .22lr), you'll definitely love the performance.