Hmm...I am not real sure where to start on this one. I think that the biggest part of this thread that was missing, was the part where the OP waited for so long to mention that hybridization was a factor of the culling.
I have been an aquarium hobbyist for about 8 years now and I am still not sure where I stand on hybridization. I am sure many of you are wondering what that has to do with hybridization at all. Well.....just type in the words "flowerhorn" on any purist cichlid forum or mention the word hybrid and prepare to be flamed.
It has gotten so bad in the hobby that there are very few sources of some species of fish that are pure. Amphilophus trimaculatus, Amphilophus citrinellus, Amphilophus labiatus, and Amphilophus festae are just a few species that have been so muddied, that in order to get a pure strain you have to find someone who has wild caughts or f1 available. The day when you can walk into ANY pet store and find them has gone. Sure, petsmart and other places sell what they "call" a midas or a red devil, but it is simply a mislabled animal.
People have been creating these gorgeous, high selling hybrid fish, but at what cost to the hobby? I personally do not have an issue with hybridization as long as the animal is sold as it is, not as something it "looks like".
I can see where the OP is coming from on this point of view. It would be very detrimental to his hobby (carpet pythons specifically not bps) if he did not cull some of his animals. IME with fish, I have sold a hybrid fish (I didn't breed) to the pet store and told them exactly what it was only to have it mislabeled and sold as something else. It can be very disappointing to buy an animal while thinking it is one thing then to have it identified as another.
However, the question has to be asked....Why even bother hybridizing these animals if it could pose such a huge threat on the purity of these animals? What happens when pure strains of them are gone due to hybridizing? Why hybridize them at all if the end result is having to cull the ones that aren't the "what you wanted"?