It is auto-generated with the purpose of maintaining the exact same semantics as the C code, with no regard to safety, best practices, etc.—of course it is messier than actual, handwritten Rust.
As c2rust says in its documentation [1], it's meant to be the first step in an otherwise manual and incremental port of a codebase from C to Rust, and the author recognizes this in their closing remarks:
> The next goal is to convert the codebase to safe Rust.
[1] https://github.com/immunant/c2rust/raw/master/docs/c2rust-ov...
