Should Rahm Emanuel have called Liberals "retarded"?

The question isn't a matter of accuracy or truth, but one of political correctness.  To be precise, he referred to liberals as "f***ing retarded," but the controversy is about the second word, not the profanity.  According to Slate,

The current version of the Diagnostic and Statistical Manual of Mental Disorders—which is used by psychiatrists to make clinical diagnoses—still employs the phrase mental retardation to describe people who score below about a 70 on IQ tests. However, most who work in the field—including psychologists, activists, and bureaucrats—prefer the term intellectual disability.

They conclude that "Government offices have also been moving away from mental retardation" - a statement that needs to be interpreted strictly in context.

Several months ago I read an article in the Minneapolis Star Tribune online discussing the same topic.

The adjective “retarded” appeared in a headline on the front page of the Star Tribune last week, prompting complaints from dozens of readers who find the word to be hurtful, insensitive and out of date. They argued thoughtfully and passionately for alternatives such as “mentally challenged,” “developmentally disabled” and “cognitively delayed.”

The Star Tribune newsroom’s stylebook governs our use of terms such as “handicapped” and “developmental disability.” Here’s the entry on mental retardation, last reviewed in the late 1990s: retarded, mentally retarded. Use these terms rather than “developmentally disabled,” a hard-to-understand euphemism.

They note that the style will be reassessed, but close with a passage from the New York Times (citing the Philadelphia Record) illustrating how much style has changed since the nineteenth century:

The most pitiable case that has yet come under the notice of the Lunacy Committee was discovered last week in Fountaindale, Adams County, where Jacob Miller, a wealthy farmer, was found living with his eight imbecile children...

The mother of this miserable family had died several years ago insane, her reason having given way under the terrible strain to which she had been subjected. The poor woman had given birth to 11 children between 1860 and 1874, and not one of her numerous offspring was possessed of a sound mind...

Five of the children are driveling idiots, past all hope of improvement... The oldest child is the worst of all, scarcely possessing the instincts of an animal... It was learned that Mr. And Mrs. Miller were blood cousins of the first degree, and to this fact alone the members of the committee attributed the imbecility of their offspring. The father, however, had no explanation for the matter, and he looked upon the affliction as a stroke of Providence...

More at the link.