> He’s pointing out that the phonetic maps are so loose and nondeterministic

This interacts with the highly inflectional nature of Greek; imagine a scheme for deciphering an unknown text into English which allowed the decipherer to insert, at any point, any word that might not be capitalized in standard English title case: to, for, the, of, and, but, with, ..., along with whatever plural or possessive markers they wished.