At the time I'm writing this, the latest commit in https://github.com/LuaJIT/LuaJIT was 26 minutes ago. There has also been a constant stream of commits over the last months (I didn't check further), but no frantic activity. Almost all commits in the moonjit history also seem to be be cherry-picks of these LuaJIT commits.
So calling LuaJIT unmaintained, and saying that moonjit "continues development" both seem a bit exaggerated to me.