More involved fixes are not something allowed in rc kernels, and Kent knew that.
Bugs are a fact of life. Bug fixes are a fact of life. Sometimes those bugs will cause data loss. Adding code in and -rc to support data recovery when a bug caused data loss to occur is a good thing for users. Portraying it as a bad thing is the worst kind of bike shedding.
If you're arguing that bcachefs is incompatible with the practiced kernel development discipline, well, I guess linus agrees.