Unsafe rust is a superset of safe Rust. They're two different languages. The OP is saying, correctly, that certain data structures are inexpressible in safe Rust. That's fine. Certain control flow structures are inexpressible in goto-less C.
I don't think "certain control flow structures are inexpressible" is the same assertion as "certain programs are unexpressible"...
After all, any turing complete system will have a similar set of computable programs as another, but they will not all have the same control structures. For example, you can have a turing complete language with no loops, only recursion. Both can express the same programs but not in the same way.
