The first thing to know about Donald Trump's alleged proposal for a Muslim registry is that it isn't a Muslim registry.
This has been lost in a freakout that has some brave souls already promising acts of civil disobedience to disrupt and overwhelm the prospective registry. The controversy tells us much more about how the media will cover the Trump administration — i.e., through the lens of fact-free hysteria — than about the administration's immigration enforcement agenda.
The source of the fracas is a comment from Kansas Secretary of State Kris Kobach, a Trump immigration adviser and (excellent) candidate for homeland security director, to Reuters. Kobach noted that the administration might reinstate a Bush-era program tracking visitors to the United States from countries with active terrorist threats. This suggestion was spun into a first step toward herding our Muslim neighbors into internment camps.