You are right, I don't know what the spider mutation is. But here is the thing, neither do you. So how can you suggest that "it is very probably to be a point mutation with a promotor controlling the level of expression and really no grounds to suggest an evolutionary divergence" ??? Sounds like your guesswork is adding up to a lot of fluff as well.
So man just happened to find the only spider in the history of the world? Let me get this right... When a spider mates with a normal 50% of the babies are spider, 50% are normal. To suggest that one spider somebody happened to find in the wild is the only one is rediculous. Even more rediculous is the idea that because we only have record of another country finding one spider ball python, it must be the only one they have ever found.
LOL!
Bingo!