You have to ask the seller what he means by a "racing keel." I suspect he means that he removed the keel and faired it to design specifications. If so, that would only be a significant plus if you plan to race the boat seriously (perhaps worth a couple hundred dollars extra). My first keel boat was a 1974 Catalina 22, my second keel boat was a Catalina 25, and, in nearly 30 years, I never heard of Catalina offering an optional racing keel.
If he has some kind of custom keel that was fabricated for his boat (which I seriously doubt), then I don't believe it would be permitted to be raced in events sanctioned by the Catalina 22 National Association.