I think their original post lays out the benefits pretty well. I think the realization of some of these benefits is debatable (for example, they probably could have made their existing Zig code faster), but others are straightforward (like having fewer crashes because more of your code is provably “safe” in Rust terms).

(I think wrapping a large, complex C/C++ codebase is where Rust often shines, if you build the right joiner abstractions. PyO3 is a really great example of that.)