No question, yes, I would let him take the day(s) off. If you're concerned about him getting behind, make an agreement with him that if he chooses to go, he has to read the texts he’ll be missing during travel time or down times after the hunt (cabin, whatever). For me, I’m not sure I’d even do that. I wouldn’t want to ruin the experience by mixing it with homework. Hunting is supposed to be relaxing. I’d let him enjoy his couple of days off. The kid can always work a couple extra hours a day for the next week to catch up. Just make sure that he does.
And, as far as the taking days off from school teaching him that’s it’s okay to cut out from school or work later in life (presumably when he’s on his own), I don’t think so, if you make him understand that he has a responsibility to catch up on the school he misses now. If he doesn’t catch up, then maybe that will affect things the next season when you want to take him hunting (i.e. you don't let him take off school again). There’s a balance in life and work. I think it is okay to teach him that it is fine to take time out of the daily grind to do what you love, as long as it is done in a responsible manner. I do not understand people that work so much that they have no ability to enjoy life. They might say something like, “I’m doing this now so my kids don’t have to.” Rubbish, IMO. The kid is gonna do exactly what you do and say the same thing his go-round in parenting. Life’s too short to miss life for work.
My $0.02