That said, this is almost too obvious to point out, but it happens to be true that the Soviet Union and Communist China (and Vietnam, Cambodia, etcetera) murdered 100 million+[1] in the name of "building socialism", and it is quite possible that the original poster knows people from those countries who lost loved ones to socialism/communism.
Seen in this light, I'm not saying that OP's phrasing was the way to go, but it's understandable that there are people frustrated by this all too common style of ignorance. It's not idealistic to actually support socialism in 2011, it's simply ignorant.
At the risk of reductio ad Hitlerum, certainly an offhand comment in favor of "rational, libertarian Nazism" would have dominated response to the essay, yet we find it acceptable for educated people to make offhand[2] complimentary references to a polar opposite ideology that actually killed many more people.
[1] http://www.amazon.com/Black-Book-Communism-Crimes-Repression...
[2] Or in this case, direct rather than offhand