As my second son was reaching 12 all he could do is talk about hunting with me. I told him if I couldn't trust him with the care and attention to detail it took to do his homework, I wasn't going to trust him with a loaded gun. He didn't take me at my word, and as a result his step sister went hunting with me that year and he wasn't allowed to even go for his hunter's-ed course! Sucked big time, but I wasn't backing down.
I told him he had a second chance, that his grandfather wanted to include him in our annual fishing trip to Canada...if he could keep his grades up. He darn near blew that one too, managed to pull D's up to a C at the last minute. He just about lost hunting once this year also but managed to pull his head out of his butt in time to salvage it (wasn't doing his homework again).
Does it hurt to take away special father son time? You bet ya. As you see it hurts both parties. But if I hadn't taken the entire season away from him last year, I would not have gotten compliance this year! He's doing better, and being more responsible, in part because he remembers having to stay home all of last year while his sister went out! And I'm sure he's working towards next years Canada trip as well.
You could cave in, make a special concession because....gee whiz, ya never know when you're gonna croak.....and you're last lesson to him will be that personal responsibility is not his responsibility. I'd rather die knowing that I left behind someone who his willing to work for his future, instead of someone who is going to sit back wondering why he can't have what he wants!