Certainly, the best arguments in favor of Shining are 1) no one else has claimed a protective role and 2) his role + your Strengthener is the current best explanation for Luna's information.
1) isn't that strong of an argument because a protective role would probably want to avoid claiming since they would be a prime NK target. 2) could have a different explanation. I think the interaction between my role and Jailkeeper does fit, as does the Gravedigger/Ninja theory, but neither fit the lock very snugly, if you ask me. At this point, I'm 50:50 between Luna's information being either one of those two theories or something that is not public knowledge yet.
The arguments against him are a) he hammered Kohai, b) Jailkeeper from Jim Moss is iffy, c) Jailkeeper is a great cover for a scum RB, d) your role does support the existence of a scum RB, e) Jim Moss sticks out as the only character not in season 1, f) scum could have used their questions to make sure Jailkeeper was a safe claim, g) there could easily be an alternate explanation for Luna's clue with two players (besides me) unclaimed
The more I think about it, the less I see a) as an argument. We needed to lynch someone, if only because we were on odds, and that was the wagon he could drop the hammer on. If he did not strongly townread Kohai, he was better off ensuring a hammer-drop than going against the flow.
With c), I'm curious if anyone else wants to claim some sort of roleblocker. If we got two roleblocker claims, even if they were different sorts of RBer, I would bet a nickel that there would be exactly one scum between them. As for b), I don't think a Jailkeeper precludes a scum RB.
Regarding e), I'm sorry if I'm forgetting, but has whiteflame said whether or not this game is based only on any specific part of the show?
f) and g), yup, there's no arguing with those.