In reply to:

The original meaning of "fungible" was that any ton of
wheat could satisfy a debt for which a ton of wheat had been pledged.
I see no way in which loyalty could be such a commodity.

bill, while the situation is not precisely analogous, could I get you to agree that (in the article at least) loyalties seem to be bought and sold like a sack of grain?

and as to "the original meaning", well I can only say that I hope to see the day when we convince you that English is a fluid, protean, and vicissitudinous language!