That scenario seems highly implausible to me. Why would someone who is annoyed by newbie questions choose a label soliciting those questions and then take the time to answer them discourteously?
Some members don't see things the way we might,
nsx. I agree with you, but I know many people that think they're helping newbies by consistently saying "do a search, it has been discussed a million times before." Obviously if a newbie sees a member with a "helpful" tag and gets that, they'd be immediately put off.
If it became necessary, we could specify that when you choose the "helpful member" label you agree to be helpful, and that failure to act consistently with that would be a TOS violation. I seriously doubt anyone would break such a rule.
Again, we all have different meanings of what's "helpful," so we'd have to create some concrete rules then for what constitutes friendly, which I think would be challenging to do. That's why I think something like what has been suggested earlier in the thread (a committee) should be set up to decide.