This is a key point that I hope they recognize and carefully consider. The difference between speech and behavior. In meatspace, these are different things, so the government can punish someone for their behavior but cannot punish someone for their speech. Online, speech and behavior are the same thing. So when someone gets blocked for, say, spamming the n-word over and over, are you blocking them for their speech or for their behavior? The blocker will claim it's for their behavior, and the blockee will claim he was censored because of his speech. Who's right?
Then it's up to the social media company to decide what to do about it. Twitter has a First Amendment of association. Twitter can ban the comments, or leave them up, or do anything in between. If Barack Obama were currently a government official, Obama would have latitude to ask Twitter to restrict N-word comments on his posts, but the First Amendment would prohibit him from coercing Twitter to restrict N-word comments, and would also prohibit him from blocking the commenters.
Note: Twitter has a First Amendment right to ban speech, not only conduct. "Has a right" doesn't mean "should", but in the first place the featured article is about a legal issue, not an ethical issue.