How much experience does he have with guns? Do you shoot a lot or is it just that you are getting ready for a hunt or two?
I was raised shooting all the time. 40 years ago when I was 8, I started shooting a 30-06 - we were deer hunting in VT. My uncle tried to talk my dad into a smaller caliber, but nope, a 30-06. I had a bad flinch for many years - just getting over it in the past couple 3 or 4 years. I shoot good but it takes so much energy to shoot good. My dad didn't do me any favors.
My favorite deer rifle is a 357 magnum Ruger M77-357. Not much noise, no recoil...peace. It is a deer killer inside of 100-125 yards. Not eager to shoot further with it.
So, be careful with him. It doesn't sound like you guys have a history of shooting a lot. 200 yards is a fair poke, especially if he doesn't have the basic foundations down: breathing, tight cheek weld, squeeze, etc.
Does the gun fit (scope height?)- a cheek pad might help too.
A pellet rifle is a good practice cause you can shoot those about anywhere, Make it fun - shoot for change (if you hit it it is yours), funky targets.
22 is great for lots of shooting - shoot for groups, small targets, etc. You can shoot a 22 at 100-150-200 yards too.
I remember a guy shooting gum balls at 100 yards with a 22 at a local range - he was having fun.
Have you asked him about the noise? My step-son has super sensitive ears and wears ear plugs and muffs...
Sorry if this is all repetitive. I paid a price for my dad making me shoot too much gun to soon. Missed plenty of deer that I should have killed due to the flinching.