his own version of linux? you mean the kernel, right?
You would think that if he decides what's in the kernel...he would atleast run his own.
as for the distro, "his own" is misleading...I doubt he writes his own programs, so maybe he likes GNU released proggies....
ok, so that takes care of the kernel and programs.
now, package management? this is where the "distro" actually comes in...i would bet that he has his own setup of how to manage his packages (ie. kinda like someone who installs LFS: do what you want, how you want it). Unless he's lazy and does not feel like worrying about his packaging system - then he'd use Debian.