I like Rust and use it full-time professionally. Unsafe is not the same as unsound. Unsound means that the unsafe code is not maintaining the aliasing invariants on references required by the language, and thus undefined behavior can leak into safe code (that is, the safe code can be miscompiled).

Known unsound code should not be merged, let alone released to production. If you have good enough tests and run them under MIRI or ASAN, maybe you can get away with it for a time, but most Rust experts would not sign-off on such a project.

If somebody put a gun to my head and told me to make the best of such a codebase, I would try to figure out how to turn off the LLVM optimizations that assume the Rust references don't alias. With these optimizations this codebase is scarier than most C or C++ code.