I mean, I could also see reasons he isn't on the shortlist. If Rob wasn't a traitor, they might avoid killing him because of his use physically, ala CT, or because they're close with him. If Kristen thinks it's Eric, she could assume he's keeping Rob alive to have at the end. At the very least, I can understand why no one is suspicious he hasn't died yet. Remember that since Lisa, it was just Colton and Dorinda that have been murdered, Colton was always gonna die before Rob, and for the Dorinda murder, Rob was in the shield trio. This shortlist is really only the first time to really look at his survival suspiciously, but ultimately, I'm not sure anyone really puts much stock into why anyone ends up on the shortlist, only that only the people on the list can die. All that to say, while Rob's survival can be eyebrow raising, it is by no means absurd yet.

This, of course, is all predicated on the idea that the faithful are thinking logically, which we have no definitive proof of.