He's not enacting a law to prohibit anyone's speech. He's simply requesting that SXSW use "discretion" in its own speech. Although this isn't the best analogy,

He's not enacting a law to prohibit anyone's speech. He's simply requesting that SXSW use "discretion" in its own speech. Although this isn't the best analogy, it's like a concerned parent writing a letter to a magazine asking them to refrain from publishing borderline obscene content. When TV/radio personalities get their shows cancelled over inappropriate comments, that's not a violation of free speech. In fact, it's an affirmation of free speech--the network doesn't want to tarnish its brand.