So what are our plans regarding this, assuming we get Crimson Flare? Or even if we don't:
Socially, the big problem is - what if he just asks Hunger something that Hunger would have to lie about, like his long-term intentions for the Temple or even something as simple as "do you have or plan to have any hostile intentions towards the Temple's society, inhabitants or Treasure?" There are ways out of this but most of them require lateral thinking to some degree unless you go Maximal Safety.
I mostly noticed vali's genius
Plan No Habla Español, but are there other ways?
Rihaku often leaves a way out of even most desperate situations, though not without cost. We can't truthfully say that we don't have hostile intentions towards the Temple, that's true, so there are two ways I can see. First is not letting the question come up in the first place - no idea what could distract him so much that it wouldn't even occur to him to ask - or we answer truthfully that we intend to harm the Temple, but in such a way that he doesn't attack us... telling him we'll replace the Ring with something better is also a no-go, because he doesn't have a reason to want that change and is content with what he has.
He's a retired marshal, and while he doesn't like their Council, he has learned to live with them. One thing we could offer him if Hunger can extrapolate information about a future Ennoblement option from the Ring's current functions is prolonging his life. He's an old guy, and apparently Soul Evocations don't do as much for that as they do for power.
Hmm, his blurb also mentions his grandkids. Now I'm obviously not suggesting threatening him with that, since we want to
avoid a fight if we can, but where do they live and what does their future hold? Are they in the Inner Temple? What will happen to his family once he dies? I would normally expect insurance that they won't have to worry about anything for a long time if the Council wants to guarantee their loyalty, but we'd seen that the Amarlt family got shafted after Vanreir's father committed some unspeakable crime. Maybe that's a direction we could dig in?
Honestly not sure how to perfectly solve all the problems, partly because it's too late here. Hopefully someone else has better ideas.