We're talking about snakes here, not dogs...
I'm not saying this is the case here, but the guy could really just have an aggressive snake. I don't care if you're dealing with balls, boas, corns, rats, etc....there are always a few plain old nasty snakes. I have one girl that's a little rough around the edges(she's a biter), and how I approach her is different than how I approach the others. No husbandry/feeding issues, just a grumpy snake. Always has been.