That sounds very fishy. Surely if Richard Stallman criticizes Microsoft, it's not a problem because it's not the *university* doing the criticism.
If the university signed a contract with MSFT prohibiting *anyone* who is present at the university from criticizing Microsoft, then it's a different ballgame and the university administration should be thoroughly ashamed of itself. And all the students there should walk around with "Microsoft Sucks" T-shirts to see how MSFT and the administration react.