Whither btrfsck?

Personally I think the thing is the same for filesystems as it is for any other major piece of software. Release early and release often. And don't simply say it's experimental, but tell people very hard that it will eat your data and that you should run it on a copy of the actual filesystem you want to restore. You also want to explicitly flag the release as alpha/experimental/eat-my-data and communicate that so distributions won't pick it up under the assumption that something is better than nothing.

But irrelevant of that: Putting the code out there doesn't make it a release!

Sure people will see it as one when you encouring them to try it (which would constitute an implicit release).
But when you explicitly post stuff (whether as a set of patch or a reference to some repository), add the eat-my-data warnings and explictly state what your intent is for posting it, than shame on any who get burned by it.

And if your intent is to protect people from themselves, than I'd say that purging your beta quality filesystem with a pre-alpha quality auto-repair tool would be the place to start ;-)