I can understand why a dealer would shy away from an M5 today. looking outside the window at the weather and then looking at the computer screen for signs of economy (whatever stands for 'economy" nowadays) plus the fact that 2002 probably can not be financed by a potential buyer... you get the idea.
Of course I see absolutely no negatives in advertising the car right here on the site. Just put as much info as you can and good pictures.