In fact, the recruiter was the one that introduced "UNIX-like" term, in a reply to second resume change. Judging from that, I'd say this recruiter is intentionally malicious.
Agree. This is a recruiter-like person. I doubt he knows at all about "Unix-like" systems. He debated about words hiding his own shortcomings. I would have replied "you needed it" to the comment "thanks for the tutorial".