2.6.21.7 fixes some bugs, I guess it's time to mark it stable and add to stable tree.
I'm not sure it's worth the effort to be honest, 2.6.22 has already entered the stable tree. I always keep the latest available 2.6 kernels in the tree if you want to stay with a branch, but getting all of the arches to mark an ebuild is a time consuming processes. If you think it's worth the time and effort, then feel free to reopen the bug.