If a father truly needs to wonder if allowing his son to skip a couple days of school to go hunting (with his father) will set a precedent for irresponsible behavior in the son's future, then there are problems in the kid's upbringing that have nothing to do with hunting.
If I ever caught myself beginning to ponder this notion, I'd slap myself before I could finish the thought. I recommend the same treatment for others though it seems too late for some.
I had daughters that had no interest in hunting. If I have a grandchild that wants to hunt, you can bet I'll take that kid out of school on opening day. If any son-in-law tries to give me an BS about setting a bad precedent, I'll set him straight then and there.