> But he is now telling his C devs they will need to learn and code rust to make new code in the kernel.
I don't think this is accurate, Rust is still totally optional. Also, the Rust folks are supposed to fix Rust code whenever it breaks due to changes on the C side. If they fail to do this, the newly-broken Rust code is supposed to be excluded from the build - up to and including not building any Rust at all.
Yes, I know the policy that has been stated and the recent docs on it (https://rust-for-linux.com/rust-kernel-policy). A good portion of the R4L group were trying to avoid this scenario due the toxicity of such a change (especially at this early contentious point, and despite what their online advocates want). I don't think the policy will immediatly change because of his statements, but I find it pretty clear that this is where he wants the project to go.
I don't think this is accurate, Rust is still totally optional. Also, the Rust folks are supposed to fix Rust code whenever it breaks due to changes on the C side. If they fail to do this, the newly-broken Rust code is supposed to be excluded from the build - up to and including not building any Rust at all.