wait do people actually think this position requires Unix (not linux) experience? I assumed the recruiter must just be wrong there.
For example, American Express has a large deployment of AIX systems and they indeed look for candidates with experience in AIX systems, although I believe someone with experience in another Unix or Unix-like system should also be okay.
But I agree that such openings are usually quite specific about which Unix system they are working with.
"Unix-like" today means bsd/linux. The recruiter did bad, but recruiters will always do bad.
If its a job you want, don't let a recruiter foible disqualify you, if you can help it.