I think you're misunderstanding the situation. Kent Overstreet is the bcachefs maintainer and he's extremely pro-Rust. He has in fact talked about wanting to

I think you're misunderstanding the situation. Kent Overstreet is the bcachefs maintainer and he's extremely pro-Rust. He has in fact talked about wanting to move bcachefs to Rust, and the userspace tools for bcachefs are already written in Rust. He's been participating in the mailing list discussions about using Rust / providing Rust APIs for the FS subsystem. I don't know who you're confusing him with, but you're confusing him with someone else.