Why Do Liberals Hate Society's Most Vulnerable People?

For some reason, liberals seem to hate society's most vulnerable citizens, people with developmental disabilities. Some blogs I read on a regular basis has shown the hate of these people that they feel they can make fun of or use as comedy props, people with mental retardation.

The Las Vegas Gleaner, a progressive blog which criticizes both liberal and conservatives recently had this post about Steve Wynn and a possible move to China. The post was snarky but became hateful in the last 2 sentences: "Or as Wynn might say, Macau is not trying to "retard" the economy.
One question, though: "Why does the cranky old fart, er, magnificent gaming industry genius, have to keep hating on Trig?" http://www.lasvegasgleaner.com/las_vegas_gleaner/2010/04/beloved-industry-titan-to-america-get-off-my-lawn.html#comments

Gleaner was looking for a quick laugh and used Trig Palin, an infant with Down Syndrome, as his foil.

President compared his bowling and his joking about Special Olympians when he compared his bowling and Special Olympians: "Appearing on “The Tonight Show,” the president told host Jay Leno he’d been practicing at the White House’s bowling alley but wasn’t happy with his score of 129. The he rolled a gutter ball by quipping: “It was like the Special Olympics or something.” http://scaredmonkeys.com/2009/07/26/democrats-and-the-r-word-obama-special-olympics-comment-retarded-term-in-house-health-care-bill-and-teaching-moments-does-any-one-ever-learn/

Rahm Emmanuel called liberal activists "Retarded": http://blogs.abcnews.com/politicalpunch/2010/02/rahm-apologizes-for-privately-calling-liberal-activists-retarded.html

Stephen Colbert calls Sarah Palin a "fu...ing Retard" http://liberalconspiracy.org/2010/02/09/watch-colbert-calls-palin-a-fcking-retard/

The Family Guy cartoon show on Fox had an episode in which they used a Down Syndrome girls as a comedic foil: "Early this morning, Fox News contributor Sarah Palin blasted Fox Hollywood for the recent Family Guy episode that took a pretty hard-to-miss jab at her special needs son, Trig Palin (Family Guy son Chris Griffin was dating a girl with Down’s Syndrome…whose mother was the former governor of Alaska). Calling it “another kick in the gut” — a reference to Rahm Emanuel’s use of the word “retarded” " http://www.mediaite.com/online/sarah-palin-family-guy-trig-bristol/

In an interview with Bill Maher, Seth McFarlane implied that President Bush was retarded and Maher found no problem using the word "retarded". http://newsbusters.org/blogs/noel-sheppard/2010/02/20/family-guy-creator-seth-macfarlane-calls-george-w-bush-retarded


Now, I will also say that some conservatives misuse the word retarded and the one who comes to mind is Rush Limbaugh.

So, my question is this: why do certain liberals hate the developmentally disabled, people with Down Syndrome and people with disabilities?