The 'R' Word

I was just watching Ann Coulter being interviewed on Piers Morgan's show on CNN.  Morgan is one of the most insufferably PC characters on TV today.  He was berating Coulter for using the word "retard" in a recent tweet.  He couldn't resist copping a "more-sensitive-than-thou" attitude - averring that "retard" is as offensive to disabled people as "the 'n' word" is to blacks.  Coulter had several reasoned responses to Morgan's charge.  She pointed out that she had never heard a disabled person complain about the use of the word "retard," only self-appointed spokespeople for the disabled.  She also noted that retard is no different than idiot, imbecile or moron; all of which were once clinical terms for persons with mental disabilities.  But she uncharacteristically missed an obvious rejoinder.  How can retard be equivalent to "the 'n' word" when Morgan can't bring himself to say the 'n' word but he apparently has no problem throwing the word "retard" around.  This is prima facie evidence that Morgan's outrage is completely manufactured.