Also remember the majority of computers in schools are in the student lab to teach students something that supposed to be useful. MS rules the computing world, teaching students how to use Linux won't give them any useful skills in a world where 90+% of the desktops aren't Linux.
If the majority of graduates are Linux-savvy, and thus reflect a preference for Linux when they enter the working world, MS will not rule for long.
This might be what they're afraid of