I'm not sure of their liability.

After all, every part of an airframe has limitations on the stresses that can be placed on the various parts. There are normal stresses you can do to the airframe, and their are abnormal stresses that would happen in emergencies. Beyond those, the airframe will fail, as a certaintly.

I think maybe, just as a hypothesis, the difference here is that the composites used in the tail don't give the same type of early warning signs that metal does. It is fine one moment and then it snaps. This is one problem with composites in general, or at least it has been.