I am really shocked that a cat association would put such an ignorant rule in effect.
I am a huge advocate of pediatric spaying and neutering, for so many reasons, I can't list them all.
I would suppose my first response would have been, no, I wouldn't sell to a breeder who doesn't early alter, however, I think one has to make the effort to know who they are selling a breeder too, and if they believe they know the ethics of that breeder. One of my mentors and president of one of our local cat clubs, also doesn't early alter, for various reasons mentioned, (finding a vet, that she trusts that will perform early altering), and she screens her pet buyers very thouroughly, she has a pet contract, very much like Celestialrags was speaking of.
So, I guess my final answer, would be yes, I would sell a breeder to another breeder who doesn't early alter, but I would have more reservations. I should also add, I have never sold a breeder as of yet.
When we first began searching for a vet that we felt comfortable with, that would also do early altering, we had difficulty finding one at first. We really believed we would be driving two hours away to a vet we did like, and then back the next day to pick up the kittens.
It turned out, another breeder was able to point me in the direction of several vets that did early alter, the prices varied, but we did find a vet close to us, who we just love. All of our kittens have been early altered and are doing wonderful as young adults.
Our 4 year old male was early altered and he has been a very large, healthy boy.
I am sure everyone has read this before, but I am going to put the link in again. This is an article that Dr. Susan Little wrote. http://www.catvet.homestead.com/EarlyAlter.html
I have emailed her early alter protocol, to many vets in our area, in hopes that pediatric altering, will soon be accepted mainstream.