Depends on the purpose, as I mention.
If the target is to be platform specific, then reducing the amount of compiler toolchains, IDE/editor plugins, and language knowledge required across team members is a good thing.
If the purpose is to go cross platform, then it is another matter.
Then again this is a matter of opinion, feel free to disagree, I am not here to change your mind.
Integrating object code into Objective C or Swift is easy, commonplace, people do it all the time.
Rust can generate object code all day, you can insist on the C ABI anywhere you need to, and then you can bring in anything from cargo you want. CocoaPods is... not cargo.