I've re-read the whole thread, and I think it's clear we are dealing with the s/z pronunciation of final S plurals as in news, rather than the phonetic value of S wherever and whenever it is seen. Therefore, his rule is correct, though it could use being rephrased more clearly to describe final s on words that exist both with and without it.
The lose/loose dichotomy has nothing to do with the 'final s' variants the thread has been about since the beginning. Anumph just assumed it was clear we were talking about final s while typing the rule the first time.
Again, we are dealing with plural final S, and 3rd person singular final S.... if the word exists both with and without the S, then the rule stated above does accurately tell us its pronunciation.