To Serve Linux...
...as in Twilight Zone cookbook type of "Serving". :-)
MS makes a cheap investment supporting a company that is very much antagonistic to Linux. SCO wants to gain legitimacy for it's claim that unix is their IP - as in lookey here judge, we got the most pervasive company in the world paying their Unix dues, why won't these others recognize the same?
IOW, it's a legal ploy. MS doesn't really give a dang whether they're street legal. They just want to cause grief for all the Linux vendors that don't pay the SCO lawyer tax. SCO just wants their mafia mobney from every Unix in distribution.