I explicitly did not ignore the option that there are possible sound semantics:

> but not necessarily for this one specifically

> Maybe, maybe not.

But "the Rust semantics" are not defined, formally. The closest we have is what Rust implements currently, and that was shown here to not be sound. Other than that, we maybe have vague ideas in the brains of some T-types members, which are not detailed enough to determine soundness (source: those type system people want to formalize the semantics so they will be).

And for the record, we know of other soundness issues where the likely resolution path will involve rejecting valid programs we accept now, and the only question is how many.