Using the lower, 1.567 ratio and assuming that that represents a 5% discount to Buffett's estimated IV, then Buffett's estimated IV corresponds to 1.65 BV.
Using the lower, 1.567 ratio and assuming that that represents a 10% discount to Buffett's estimated IV, then Buffett's estimated IV corresponds to 1.74 BV

Maybe he is telling us instead "I see no good opportunities, and I rather invest some cash in Berkshire than all in 5% Treasuries"?

Be careful with your "Warren's view of IV is what he is willing to pay for a share of Berkshire plus at least 5%-10%". That was true, but I think you are too stuck to his old "buybacks only with a discount to IV". In the Q&A he made it quite clear that in the current environment he sees no good opportunities to invest larger sums. I think to remember him saying "I am cheap" in the context of current valuations, indicating that everything that might move the needle simply is too expensive for his taste. And this is going on now for a long time.

This might have changed his opinion on buybacks from many years ago, on the required discount. It's a matter of adapting to a changed (more expensive) environment. As more expensive that gets as more sense buybacks make at a smaller or even no discount. Better to invest some Billions in a Berkshire that returns 10% than in 5% Treasuries, if leaving still enough ammunition for elephants should the environment changes again (my impression because he was so insistent on a large cash position is that he sees it quite likely that there will be elephants in the room again).

Just saying you should be careful to routinely add 10% or so to his highest buyback price and to think that still must be Warren's lowest estimate of IV. The environment changed and his views might take that into account.