It was a joke in response to the "grilling accident" comment. The guy was apparently by the buses, and this is not the place that one normally has a tailgate party. Parked between a bunch of diesel buses, most of which usually keep their motors running a good part of the time?
Spot on observation, livius.
Ah, so. Wink is difficult to see in text, sometimes. Unless made explict, anyway. ;)