Why not give him a day or two a week for his old favourites, so long as he sticks with Primal fare on the other 5-6 days? Or choose 4 meals -- he can have whatever he wants for those four meals, so long as he gives you X amount of time in advance. Try to keep them on the weekend or near the weekend, though, so he can gain a few days of feeling great thanks to Primal fare.
So maybe Monday - Thursday is all Primal, with Friday supper, Saturday lunch, Saturday supper and Sunday lunch being whatever he wants? Gives him some control over it while giving you a chance to give his body a chance to feel the positive effects of Primal eating.
Just a thought.