A really GOOD primer, like BIN or KILZ shellac, will minimize penetration.

But if he's a heavy smoker, strippable vinyl wallpaper might be best. I know my sister spent almost a week scrubbing out our uncle's house to get the tobacco stench out.

>>> Is there a way to put a quiet "Bath-fan" fixture in there somewhere?
* There are some motion-activated ones, and this would be a "G*dsend" for minimizing smoke build-up...PLUS a little healthier for others in the home.
* Yes, it would be a little wiring/ducting, but may well be worth it. If you can get at the room from an attic, it would be fairly easy.
* In THIS case....THE SHINIER THE BETTER for the paint.
* Glossier sheens like Satin & Semi-gloss have a tighter surface film, therefore most resistant to contamination. My preference would be S/G here.

Wallpapers absorb stuff too. Unless it's an extremely slick vinyl paper...
* This may be deserving of a "2 primer" system.
* 1st primecoat...Zinsser's BIN Shellac-based primer.
* 2nd primecoat...Use a good wallpaper primer, like Zinsser's "Shieldz".
* Subsequent paper-removals will be much easier. Apply a good full coat.

Faron