eric - reading over at howardforums, it looks like VibeTouch is disabled in the silent or vibrate profiles, but no one has asked if it can be turned off for other profiles. A post asking the question over there might clear things up, and there might a "seem edit" (phone hack) to permanently shut...
an older lady in our neighborhood loves to clip her flip phone over her thong strap and walk around with it - i certainly don't recommend that. I think belt clip/holster might be the way to go, unless she likes stuff hanging around her neck. If she really does travel as light as you say, I would...