I don't think it was a work. It's definitely a weird angle to get finished at, but my guess is that it was a hybrid choke/crank. Chael (appropriately) wasn't respecting the threat of the inital standard figure-four RNC because Tito was too far off to the side. The chin movement was because he was trying to sit up and he knew that Tito was only using one arm at that point (this was a mistake, because it let Tito get on his neck). At the end, however, you'll see that Tito switched to a gable grip and dropped his left elbow behind Chael's back. The leverage you get from that is horrific and it's totally reasonable to think that the forearm on the side of the neck was enough to get a tap either via choke or spinal displacement.
Source: I am a BJJ brown belt.