The "interoperate easier" idea is a trap for both C and C++ and worth avoiding because in fact they aren't quite compatible, so you're making both languages worse to achieve this. I don't much like C++, but if you must use C++, actually use C++ and forget that it's sorta kinda "compatible" with C.
I know they are not 100% compatible, but they are 99% compatible, and that's much better than Rust.
It's easy to make it compatible by not using fields called "class", or using #ifndef __cplusplus, most C library headers are actually like that. But not the Linux kernel because they refuse it.
That's why I'm saying that the choice is not a technical one.
You can create headers that are usable from C and C++, but you have to actively maintain it that way. As C headers tend to not have function definitions in them, it's fairly easy to avoid the C-only features.
I doubt that Linux headers give a damn about usability from C++ though.
