Hi,
No official packages depends on lua-posix and only two AUR packages depends on it (1 vote each: lush-git and zile-git). If it were to be in [community], lua51-posix or a split package with both lua-posix and lua51-posix would be a better candidate, since lua51-posix is used by more popular packages (ulatencyd and ulatencyd-git, 100 votes in total, but unmaintained, status unclear). Moving to AUR.
aur-general@lists.archlinux.org