I agree that Oberlin, as a private employer, has the right to restrict the speech of its employees in certain ways. However, it also claims to be a university that respects academic freedom. It has shown that it only does so up to a certain point. Again, it can do that.
And maybe it’s better to pretend that it’s not about the content of her speech. Perhaps that will provide a bit of shelter to the next person who is being ousted for unacceptable speech.