It's in the article

The promise basically *only* covers a *complete* implementation of the spec. And the spec is buggy and incomplete.

So if you reduce the spec to logic, you get something like "A = not B" and "If A and B then you are safe". Putting the two together, the only possible logical conclusion is that the promise is worthless, and you are not safe.

So saying the promise isn't worth the paper it's written on is NOT FUD. Just applying basic mathematical logical reduction shows that the promise will self-destruct. So you can't rely on it.

Cheers,
Wol