Trump uses Berlin attack to argue for Muslim registry: ‘All along, I’ve been proven to be right — 100% correct’
1) All along, Trump has been proven to be a bozo.
2) Even if he were a genius in this case, a Muslim registry would be 100% unconstitutional. The First Amendment of the US Constitution, with the part which is relevant to things like a Muslim registry in bold print, reads:
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
There's no reason to think that Trump has ever read the Constitution. No sign of it. But, assuming he's not impeached and removed from office too soon, he's going to become very familiar with the last part of the First Amendment, about how all of us have the right "to petition the Government for a redress of grievances."