While I absolutely think you're taking a stand in the wrong fights, like I don't see why you needed to push it so far on this hill in particular, I am sympathet

While I absolutely think you're taking a stand in the wrong fights, like I don't see why you needed to push it so far on this hill in particular, I am sympathetic to your argument that experimental kernel modules like filesystems might need a different release approach at times. At work we have our main application which also contains a lot of customer integrations. Our policy has been new features in trunk only, except if it's entirely contained inside a customer-specific integration module. We do try to avoid it, but this does allow us to be flexible with regards to customer needs, while keeping the base application stable. This new recovery feature was, as far as I could see, entirely contained within the bcachefs kernel code. Given the experimental status, as long as it was clearly communicated to users, I don't see a huge problem allowing such self-contained features during the RC phase. Obviously a requirement must be that it doesn't break the build.