While David is correct about the meaning of "alternative", at least as it was originally defined, it is not just bridge that uses the word to mean more than two possibilities. It is quite common, at least in the US, and in fact Merriam-Webster online defines it as "two or more" choices. I suppose that, like Nero Wolfe's reaction to the change in language involving the word "contact" (His sidekick Archie Goodwin found him in the office one day, ripping pages out of his brand new Webster's Unabridged Dictionary and burning them in the fireplace. He asked Wolfe what he was doing, and Wolfe growled "contact is
not a verb!") we should deplore this evolution in language, but in fact language does evolve, and it seems that "alternative" has done so.
I would make another point, though. This isn't a regulation we're talking about. It's an interpretation of law by (technically) a Zonal Authority. In fact, the ACBL asserts the right to change the law in whatever way it sees fit, within its jurisdiction. So the ACBL can, it claims, define "logical alternative" in whatever way it likes, notwithstanding Law 16B1{b}, and notwithstanding a statement (should one be made) by the WBF that the ACBL's definition is incorrect in law.
I suppose that if the ACBL can do whatever it likes, it can change the meaning of alternative to "
one or more choices", too.