That's a good point. I don't know why he's not registered or why he has a tracking chip if he's not running the marathon. As for the lettering or coloring of the lettering or bib, here's a picture that shows a runner with orange lettering and orange at the bottom right of their bib. Possibly there were different colored bibs for different runners or different classes of runners or something? And the guy in front of him has blue lettering on his bib just like the guy in question.
marathonpix : photos : 7)New York Marathon 2007 Mile 26 (2:24->2:44) : Ny Marathon 2007 ~ Mile 26- powered by SmugMug
I'd love to hear some answers from the NYC Marathon organization about if she was allowed to run under a different name, if others were allowed to run with her who weren't registered, if they knew in advance that someone else was going to wear her chip, etc. People make special considerations for celebrities all the time that normal people aren't granted.