If I'm to put a guess to it, as I've just played through the Zhokar route, the missing CG is a "realization" scene. You have to go back to Aris, Day 7, and make three choices: 1) go out of your room in the nude (which will happen automatically if you're at least Barbaric 1), 2) use the restroom instead of going back to your room, and 3) suck the cock that appears through the gloryhole. It's on the Zhokar route that you realize who that cock belonged to.