This is true, but I would imagine that, if not in the job description, if a really specific kind of Unix experience is required, it would come out in the exchan

This is true, but I would imagine that, if not in the job description, if a really specific kind of Unix experience is required, it would come out in the exchange - and be really OS specific and actually say - True64, AIX, Solaris, etc. "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.