Academia, and the Ivy League in particular, prides itself on being rigorously open, on providing broad access to all knowledge to advance intellectualism. In this regard, academic institutions often attack governments and corporations that intend to limit its free speech, but on the rare chance that this spirit of openness works against the institution, they take a hard liner approach to censoring it. The basic reaso…
The concept of tenure is definitely somewhat controversial, but it is incredibly difficult and rare to fire tenured professors. I doubt you could cite many if any examples of professors losing tenure because they're not publishing. (Although sure professors who don't publish probably won't receive tenure in the first place)
Also, keep in mind that a good many tenured professors are still in "soft money" positions, and have to bring in grant support for parts of their salary.