AHA!! A black percula is much more expensive around here than a clarkii. Hence, the LFS's statement. Perc's second white bar typically bulge forward whereas clarkiis do not. Also, clarkiis are rounder in overall shape than perculas.
Burt looks like a Clarkii clown. In all likelihood, he won't pair up with a percula (true or false). He may allow the perc into the BTA as I've seen different species of clown sharing a LARGE sebae before.