I've met Mike Pall in person. I've worked with him some since I helped facilitate a sponsorship from Google (
https://opensource.googleblog.com/2010/01/love-for-luajit.ht...). A lot of his work on LuaJIT has been supported by various sponsorships (see:
https://luajit.org/sponsors.html). This gives him a lot of freedom to work the way he wants to, instead of working as part of a larger organization.
Also note that the sponsorship page says that Mike is currently working on "unrelated projects", so apparently things besides LuaJIT are keeping him busy now.