I probaly would have mentioned that I have a lot of experiance with balls, and that perhaps a baby wouldn't be a good idea. Then mentioned the proper setup, and suggested that he research it a bit more so he didn't spend lots of money for a pet that his son might decide he didn't like, since it wasn't assured that he could return the equipment for a full refund since it would be used.
If you are non-confrontational, and calm, act disinterested and appeal to the money side as well, you'd probaly get a better reaction than just blurting out "What are you a moron?" which is what lots of us would no doubt LIKE to say when confronted with the disposable pet attitude. To us, the reptiles are beloved valued pets, members of the family, and investments. To them, they are a toy to keep a kid amused, and therein lies the idea of appealing to the money side. If they realize that they'll spend a significant amount of money to be sure that the snake doesn't die outright, and that they can't get that money back by returning the equipment, then they might think it over.
I think ball pythons are a fairly easy snake, compared to many others. Hatchlings aren't as hardy, and without a proper setup, not even subadults will thrive. They all deserve at least the minimum setup.
It's similar to the fishtank syndrome. Someone buys some fish and a ten gallon tank, with a cheapo filter. Pretty quick you're bored with it, and you want better fish, or you give it up. Better fish means a bigger better tank, with better filters... a heater... special lights maybe... and then you might be set up properly. But it doesn't mean that those first fish suffered any less. We just need to head off the impulse buy and get them to go for the proper smaller set up to start with.
Wolfy (who would prefer that NO pet ever be a impulse buy)