What's crazy is that MkLinux was actually Linux-on-Mach, not just a baremetal PowerPC Linux. The work they did to port Mach to PowerPC for MkLinux was then reused in the port of NeXTSTEP Mach to PowerPC. Everything was very intertwined.
Also, MkLinux wasn't that stable. I experimented a bit with it at the time and it wasn't really ripe for production. It kind of worked, but there would have been lots of work to be invested (probably more than Apple could afford) to turn this into a mainstream OS.
