Removing someone as a maintainer is not equivalent to banning Russian contributions. Linux fundamentally cannot stop Russians from using, modifying, redistributing and upstreaming code to the Linux kernel.

Hrm. They "Linux" could stop "upstreaming" Russians "directly" by identifying trusted developers and using them then rejecting their contributions.

They couldn't stop "down streaming" by preventing some developers from forking Linux and doing whatever.

This has nothing to do with licenses, and just about code availability, which I assume you are focused on.

There absolutely is a chain of trusted developers for the Linux mainline kernel that could be locked down to prevent Russian contributions.

But that's not what's happened so far. So far they removed Russian identified contributors from a list of developers.

The title said "contributors", not "contributions".