contributors will only ever contribute code to the mainline kernel

Not if they're all banned. Accuse them of using the wrong pronouns or saying nigger. They treat any denial of an accusation as proof of guilt.

Then welcome them to contribute to the fork, which doesn't have to be from before the code of conduct. You can fork the latest kernel and remove the CoC. It's not a license. Take the Rust bits and RIIC.

contributors will only ever contribute code to the mainline kernel

Not if they're all banned. Accuse them of using the wrong pronouns or saying nigger. They treat any denial of an accusation as proof of guilt.

Then welcome them to contribute to the fork, which doesn't have to be from before the code of conduct. You can fork the latest kernel and remove the CoC. It's not a license.