Why do you assume that identifying himself would diffuse the situation?
It might not have. Or it might have. We'll never know, will we? Because George never tried.
Obviously just a WAG, but one could surmise that if he says 'I'm with the neighborhood watch, everything OK'? or something like that, from Martin's point of view "the creepy guy that's been following me around in a car for the last couple of minutes and is now out of the car chasing after me" becomes "concerned citizen just making sure everything's ok", and maybe the talk baskeball for a few minutes before heading to their respective destinations.
Obviously that's pure specuation.
Anyone know if the Neighborhood Watch had rules & guidelines drawn up? I lived in a community with a very similar program many years ago. Everyone had maps, relevant phone numbers, and four or five guidelines on a laminated card handed out to patrolers. In addition to a small map of the particular area that person was patrolling, the card had emergency contact info and a reminder of what to say and do when confronting someone. The two key guidelines were 1) key responsibility was to observe and report; let LEOs do the arrests and such, and 2) identify yourself by name and association (Hi, I'm John with the NH, is everything OK).
If nothing else I hope NH programs start implementing these guidelines if they haven't already.