Because Americans react to some words in a Pavlovian manner. It's a way of turning their independent thinking capabilities off.
For instance, white collar criminals who engage in predatory activities always use the words "free market" as a shield. If you keep attacking them of wrongdoing, you are automatically labeled "anti-American", "socialist", "communist", "liberal" or whatever. What is more interesting is to see people who are exploited and raped on a daily basis by the so-called "free market" to defend it so passionately as though they benefitted from it. Reminds me of a homeless bum I once saw in NYC... some girls wearing Obama stickers walked by and the dude started shouting "he's a fucking commie!!!!" I didn't know whether to laugh or weep. BTW, the dude was black and a Vietnam veteran.
Don't get me wrong, I am all for free market, but we don't have one in the U.S. and we never had one. The country is run by the cartels, for the cartels. Whoever points a finger is bashed, sometimes even invited to move to France. It's quite hilarious, really... and also sad.
I think he was being sarcastic. At least, I hope so. I hope the educated on Hacker News know that socialism is actually an established word with an established definition (equivalent to Communism) from Karl Marx..
As an immigrant / entrepreneur trying every thing I can to legally work for my startup full time in the US, I'll seriously consider Canada if I fail.