It's stupid, he will find another way to gamble, there are plenty of other sites where you can gamble, disabling it on one wont solve his issue. Freebitcoin also makes a substantial amount of money from their betting option, I'm fairly sure most newbies just gamble their few earned satoshis most of the time. I know I do, I like using it as a bonus to gamble with it, risk free gambling.
Yeah, I think it's not a helpful idea at all. But I guess in the end, there's no harm to implement it.
Or maybe, allow users to set their accounts into separate sections. Like have the BTC earned into a fixed account where the automatic savings interest can be credited to. And if they want to gamble, they have to transfer the money out into gambling account, where it won't earn interest but can be used to gamble? Just to avoid mistakes of betting max.