"Anyone who know the system can easily learn it" he said with a sniff.
Yes, the similarity to Prolog lets you draw on a vast pool of Prolog programmers out there.
I mean, I studied a variety of esoteric languages in college and they were interesting (I can't remember if we got to prolog tbh but I know 1st logic pretty well and that's related). When I was thrown into a job with SQL, it's English language syntax made things really easy. I feel confident that knowing SQL wouldn't oppositely make learning Prolog easy (I remember Scala later and not being able to deal with it's opaque verbosity easily).
Basically, SQL syntax makes easy things easy. This gets underestimated a lot, indeed people seem to have contempt for it. I think that's a serious mistake.