I am still sticking with C. griseum. Sharks of the World vol2 - punctatum is the only species of Chiloscyllium that has concave dorsal fin margins. The shark in question clearly does not. Also, the second dorsal fin of C. punctatum has a longer attached base as seen in the pics I posted vs the photos he posted, where it doesn't appear to. Third, the intra-dorsal space is shorter in C. griseum. There is also a noticable difference between his shark and the control photos. Last, look where the dorsal fin begins as compared to the pelvic fins. C. punctatum's dorsal fin is set far anterior - almost both beginning together. With C. griseum, the dorsal fin is set back a little, over the second 1/2 of the pelvic fins.
Compare the examples posted. I've given five reasons why this is not a brownbanded. Despite the residual banding, as coloration is often the least important characteristic , I argue that this is a C. griseum (grey bambooshark). I think your LFS owner is correct.