Safe Rust is memory safe when used exclusively while unsafe Rust is obviously not memory safe, and a mix might also not be. If you use unsafe blocks carefully in Rust it is still quite memory safe but if you use unsafe blocks carelessly is not very memory safe. My favorite example is the CVE in a matrix transpose function: https://github.com/advisories/GHSA-5gmm-6m36-r7jh A similar error in C would be taken by Rust proponents as clear sign how dangerous C is. Overall, in practice, the safety of Rust is not so clear as proponents claim, except when strictly sticking to the safe part.

I think the experiment is a mistake and the kernel would obviously stay relevant even without this. But I am happy to let Linus make this decision. I just think it is a poor decision.