This parting shot sounds pretty dire

a bug in safe code can easily cause unsound behavior in your unsafe code if you’re not careful.

That’s definitely not how it should be. Fortunately, I think I disagree with that, since miri points to the “real” buggy code:

unsafe { inner.as_ref() }

As opposed to the article, I’d argue this code is not correct, since it did not account for alignment, which it must (I mean, by standard use of the word unsound this is unsound, since it can be called from safe code introducing UB). Or am I wrong? Is the fundamental value proposition of rust moot?