So I emailed the StarWarsAficionado author and he got back to me with some pages from his ROTJ issue.
(This is the issue in question, I believe https://www.jedinews.com/misc/articles/star-wars-aficionado-issue-14/)
He says that the information about the Lightman comes from a conversation with Antony Daniels at a Star Wars Celebration as well as the Peter Diamond interview.
In response to Hoop’s original question about where the scene was supposed to be, the author says that the scene was intended for Threepio’s initial foray into the palace, where he would be led down the hallway toward the throne room. This sequence was ultimately cut and replaced with a lengthy shot of the droids following Bib into the darkness, watched by the Gammorean guard in the foreground.
The other shot of the Lightman emerging from the Rancor passage would presumably be one of the random background appearances, as well as the shot of him behind Han and Luke in the recently discovered image.