Putting in the work is one thing, which is what the Rust-in-Linux people are also doing, but there's also the political requirement to force maintainers to accept it. Android was big enough, and happy enough to fork seeing as it had already done that before, that it forced a lot of hands with top-down mandates.
Rust, despite having Linus' blessing to be in the kernel, is still just getting rejected just because it's Rust, completely unrelated to any technical merits of the code itself.
