Standing behind the open and casual use of racial slurs isn't advocacy of freedom of speech. It's advocacy of a specific kind of hate speech that is only used when someone intends to vilify and direct hostility towards a marginalized minority.
In these days of digital sharecropping and social media saturation, the proscriptions on de jure government activity are much less involved with routine everyday freedom of speech.
I didn't think Tay's tweets were a big deal. I didn't think Microsoft's apology was either. But some people have a strong persecution complex and are offended that you can't make racist comments on Twitter.
Both the Verge and Engadget shut down their comment forums because they got tired of racist and sexist comments. I wonder if HN will root out the bigotry here.
Hate speech, in the broader form of being speech that vilifies marginalized people is rampant throughout society and it's completely hypocritical to pretend most of us don't do it. Look at any workplace lunchroom, or any group of friends hanging out in their house, or any school, any gossiping housewives, 99%er protesters, etc. Just about everybody vilifies vulnerable people. Not always categorizing them by race, but sometimes by personality type, job, country, city, status as a customer, company they work for or individual identity.