In my opinion, the popularity of a UNIX platform is tightly tied to
the availability of the platform at university.
That's a very good point. But going too far in that direction may have been a problem too. My understanding is that Omron's Luna 88K line was very closely tied to the education market. It ran a customized version of Mach, so in some sense I suppose they were tied to CMU from the get-go, and my understanding is that they courted the education market heavily. Oberlin College was given, outright, a four processor 88K Luna. Today I'm not sure you could find a running Luna if you wanted to.
-Henry