We didn’t want the audience, especially the younger audience, to think that 1962 Las Vegas was a place where you had a lot of black people sitting in the audience at nightclubs, or enjoying themselves at hotels and casinos. That just didn’t happen. So by having someone of Sisko’s historical understanding questioning that fact, we could clarify before we got him to Vic’s that he’s well aware that Vegas was very, very, very white.  Star Trek Deep Space Nine Companion