Okay, my explanation: Vic Fontaine, the hologram, is a recreation of Vic Fontaine, an actual 20th Century Las Vegas entertainer (brother of Vince, we’ve covered that). In the alternate universe, the real, 1960s Vic Fontaine was flung forward to the 24th Century by a space-time anomaly, or some weeping angels or some shit, and turned to crime to survive. It’s a sad story.
