[smolder]

In addition to what others have said, since there is a plan to introduce Rust kernel modules into the Linux kernel, being able to compile with GCC helps avoid dependence on another toolchain, which was something I've seen mentioned as a concern w.r.t. Rust in the kernel.

[steveklabnik]

To be clear, while it's a concern some people on the internet have expressed, it's not an actual problem for landing the current work to get Rust in as a framework for writing drivers.