That's rather beside the point, surely? Some categorisation is necessary in order to make things manageable. If you advertised yourself just as "musician", for instance, I doubt if you'd find yourself terribly popular when you arrived at an event that thought they'd booked a string quartet; especially if you started talking dismissively about pigeon holes...

I'm quite sure that you've found youself in comparable (though perhaps less extreme) situations over the years, so you'll know what I mean. You needn't worry about having started the singer-songwriter diversion, though; it would have happened soon enough anyway. There are always people who will ignore the question asked and instead answer one of their own invention that they prefer (witness the current accordion thread); what's a bit depressing is that, when challenged, they sometimes cut up nasty like that fellow earlier. Oh well.