If the US is such a free country, then whyr Americans reprimanded/have to face consequences for the following?

Don't know about the Sheehan arrest, but the other examples don't fit. They are in fact great examples of what a free country this is. You are free to avoid or even heap scorn on anyone you choose for any reason, so long as you do not threaten or harr them. No one was ever arrested for using the "n" word, although Michael Richards certainly regrets the free choices made by people in the entertainment industry after he used it. David Duke is not serving time in prison, but perhaps he regrets all the free decisions made by political leaders everywehere to reject him. Norman Finkelstein was denied tenure at a major university, as many istant professors are, sometimes unfairly (that's life), but he has is doing quite well and doesn't need anyone's pity.