Is he not eating or acts like he is in pain? How about just cleaning them? I give my cats Oratene, a water additive that helps with tartar. I have used it for years, and no more dental problems.
If nothing else, perhaps just get his teeth cleaned by a Vet. To automatically suggest all his teeth be pulled seems like overkill to me unless there is much more to the story.
DId the vet not give you an explanation as to why they want to pull the teeth other than the red line? I think you should consider getting a second opinion. We had a kitty years ago that had to have all her teeth except for the fangs pulled due to Stomatitis. She was part Siamese. First vet who did a great job with her saving her life - she was very ill when we adopted her, however wasn't very good at explaining things. He said on her first check up after she was healthy that "she needs to have all her teeth pulled". No explanation. Took her to another vet for a 2nd opinion. She had the same diagnosis but gave us a detailed explanation as to why. She also had us go to a dental specialist to have the extractions done. She became our regular vet for for many years, until we moved out of the area. She was a fantastic vet and we still miss her. Went through 3 vets where we live now before we found a practice we like.