If he says you are too young just to be nice about your age, then nobody can comment. However if he says it is a reason for not getting a bypass, he is not a dr and I would stop going to him and maybe even turn him into the authorities. Age can not be a reason, had mine at 41 and there are those with a bypass at a younger age than I.
Your Doctor is nuts. Ask him to have a meeting with me, I had a triple bypass at 48. I agree with RadioAstronomyObserver, I would get him seen to. Sounds like he came out of a christmas cracker