When Trent calls Darius a “terrorist,” he’s exposing his own ignorance—not all people who live in or are from the Middle East are terrorists, of course. Still, Darius can’t escape that he’s living in a post-9/11 world, where this kind of bigotry is unfortunately common. Both he and Mom, he realizes, have to figure out how to deal with this kind of bigotry, and here, Darius seems to realize that there’s no perfect way to do this. The insult is going to hurt either way, as it makes Darius and Mom acknowledge that there are people in Portland who believe—or at least think it’s okay to joke—that all Middle Eastern people are violent.