Rand Paul has been signalling this turn for years now. It's only because so many people in the liberty movement either agree with his prejudice or are so desperate for mainstream influence that they wilfully chose to ignore the signs he was making all along.
Mostly I'm just sad, because libertarians always do this, especially around issues of bigotry. We don't want to interrogate people who associate with us (at least not if they come from the right), we don't want to be "divisive," we don't want to apply "purity tests." So guys like that spend years being associated with libertarianism, keynoting libertarian events, being treated like rockstars.
And then, inevitably, the mask slips and everyone finds out what they already knew, and then we have a hard time disavowing it because we all knew it for years and did nothing.
Rand Paul never lied about who he was. Every awful thing he said last week was perfectly consistent with the position he took on the Muslim Ban two years ago, and that was perfectly consistent with his anti-refugee invective years before that. He was telling us this all along and we just pretended we didn't notice because it was sweet to have access to a US Senate office and because 30% of the movement is a personality cult for his father (who, by Rand's own reckoning, must hate this country too).
Oh well, just thousands more people associating this anti-immigrant, anti-refugee, anti-Muslim sputum with libertarianism because we can only be bothered to police our brand in retrospect.