It's not pointless. For a start it frees you from the C toolchain so things like cross-compilation and WASM become much easier.
Secondly, it's a sensible first step in the tedious manual work of idiomatic porting. I'm guessing you didn't read the article but it's about automating some of this step too.
The big bloaty part it the rust toolchain, not the C toolchain. But this beside, you are now free from a C toolchain and have unmaintainable automatically generated unsafe Rust code. Don't see a win there.