I hate it when the left confuses freedom of speech with freedom from repercussions of one's speech. Ms. Ronstadt was not prevented from voicing her opinion. She was not thrown in jail. She was given freedom of speech.
Moore and his ilk just don't like that the audience members were allowed their freedom of speech to boo her, and that the Aladdin hotel and casino was allowed its freedom of speech in making the safest business decision and tossing the walrus out on her whining butt.
While singing there for hire she is an employee of the casino and represents them. Image if, during one of my lectures (I teach at a university), I told my students that Auburn is a corrupt, evil institution and the students are wasting their time taking classes there? (Well, Alabama fans would agree, but it does a diservice to my employer.) We have free speech, but come on, Moore, nobody can be this seriously stupid?