You're not likely to carry a large enough air supply to power an air drill. Also they are loud and may attract more attention than needed. While it is true that electric motors may spark from brush to comm, they are generally shielded and far enough away as to not ignite vapor.
I've seen arcing quite clearly from inside a tool's housing from time to time and I wouldn't want to be drilling into a tank full of flamable shit with one, particularly from underneath. I didn't want to get too involved in the logistics of gasoline theft. I just didn't want anyone to be burned alive as punishment.
Besides, if you can afford a cordless and a hole saw kit then you can afford gas. Unless you stole the drill. In which case you ought to pawn it and buy the gas so you can afford to drive around and steal more drills.
Bet this'll power your drill, stud.
