The fighters aren't *inexpensive*, but not hideously costly either.
Also, the pilots like to spend as much time out on patrol as possible, to
garner more flight pay. Keffer's squad was already out earlier (as noted by
Sheridan); Keffer chose to stay out a little longer doing a bit of
reconnaisance. Most of the hassle is in prepping the ship for launch,
maintainance and so on; once it's out, it's just a matter of a bit more fuel.
If he left *strictly* for this purpose, then yeah, they'd nail his butt to the
flight deck. But since he was out anyway, it's not as big an issue.

jms