To start with, that article he posted is worthless. It seems to be based on a false viral graphic that did the rounds. Some quick Googling found that Muslims aren't banned from entering Japan or becoming naturalized citizens. This article details further.
Second off, yeah, they would be the bad guys if it were true. Barring an entire religious group based on the loathsome actions of a few is... I don't think "horrible" is the best word. "Cowardly" is dead accurate though. It's telling people that we're so afraid of the harmful attempts of the dismal few, that we'll shun and isolate ourselves from the many. Argue the merits of whether such an action would actually keep people safe, but I'm frankly more worried about the alarming rates of school shootings, drunk driving, and and corporate fraud that seem to go unstopped. Regardless, it sends a clear and distinct message to Western-hating radicals:
We fear you.
__________________ Recently Produced and Distributed Young but High-Ranking Political Figure of Royal Ancestry within the Modern American Town Affectionately Referred To as Bel-Air.