Part of what makes me squeamish about waiting is I've seen too many 10-to-14-week-old litters in shelters wiped out by parvo to believe there's anything maternal left protecting them. Since you can't know how early the antibodies are dropping off, you're rolling the dice by waiting so late, and missing a window to start the vaccine series. The earlier recs are to account for that.
I would LOVE a breeder like that. Just keep your puppy safe and away from other dogs/dog parks/etc. until then and you're bound to have a healthy dog later in life. I am totally opposed to injecting puppies over and over and over again in hopes that the vaccine will take. My last two pups had their first round of puppy shots at the breeder (unfortunately) and I only gave them parvo and distemper vaccines later, at 20 and 22 weeks. Then rabies after 6 months by law. I will only give rabies now as required by law. Of course, we don't travel or show.