maybe Plan L from outerspace?
Not sure how accurate it is though I installed MS Xenix once. The SCO partner mentioned is not the same SCO as the recent troll.
Then in 1985 MS started partnership with IBM over OS/2. Later they pulled out and did MS OS/2 with Lan Manager for servers before doing first NT release, which was NT 3.1. Later MS bought in Services For Unix for NT which was later rebranded. So the current Linux subsystem option is nothing new.
Any sensible company keeps their options open.
I dumped all my remaining NT3.5x and NT4.0 technet, MSDN and MS Select resources this week.