This is interesting - I'd no idea so many people felt so passionately about this!
1. I personally can't see why you wouldn't cross two members of a species*, no matter how different they may have become over the years. It's not a "waste of genetics" at all. In fact I might even argue it encourages genetic variation in stocks that may become inbred after long enough in captivity - look at pedigree dogs and horses. There are breeds of horse within which it is almost impossible to find breeding partners tat aren't related in the past few generations because nobody ever bred out, to retain "purity" in the breed, to no advantange but having very pretty and very stupid horses.
I can't see a reason for people to be so violently against this, provided of course that cross-bred snakes are sold as what they are. Has anyone observed health problems in these snakes? Are they likely to be more aggressive? I'm just not seeing what there is to object to.
2. *By the traditional zoological definition, that a species is a group of animals which can produce viable offspring with one another.