On Monday following the bombing President Obama refrained from calling the Tsarnaevs (who at that point hadn't been identified) much of anything. He said, "What we don't yet know, however, is who carried out this attack or why ... Whether it was planned and executed by a terrorist organization, foreign or domestic, or was the act of a malevolent individual." The next day he declared the bombings an "act of terror," which would make the brothers terrorists, a labeling supported by the detail that Tamerlan Tsarnaev's name had been added to terrorist watch lists by the FBI and the CIA, as well as the news that the two had hatched a plan to bomb New York—not just "party" there.
Presidents can't very well call people bros. But the general public can, and did. Steven Poole, author of Unspeak: How Words Become Weapons, told me, "Evidently bros has a recognizable meaning, denoting a particular type of young American male — people calling the Tsarnaevs 'bros' were presumably expressing surprise that such people could be bombers, as well as delighting in the double meaning, for the bros were actually brothers too. Compared to calling people terrorist suspects, which unfortunately has seen a resurgence thanks to these events, or even evil folks, as George W. Bush once memorably put it, with a weird combination of theological judgment and domestic homeliness, bros is almost friendly, and certainly less prejudicial."
Bros isn't synonymous with evil, with terrorists, or with suspected bombers. Bros are far more mundane than that, as Malone explains, just kind of "alpha male idiots," a kind of folks, maybe. Bros are not by definition "armed and extremely dangerous," as appears on the FBI's wanted poster for Dzhokar.
That evil-doers or terrorists might resemble the average bro, though—or, for that matter, a 19-year-old kid—is its own kind of terrifying. We don't want to think that people who do such things could be familiar, resembling the boy next door or that quiet, otherwise unremarkable neighbor or coworker. (Even if some people thinks this is what the media is trying to portray.) But evil doesn't wear a certain kind of hat, have a certain color skin, go to particular school, or live in a particular place. Terrorists could look like bros, but they could look like anyone.
Malone suggests we retire a word like bro "when it becomes more empty than the things it supposedly dismisses," and she may be right. A meaningless word is of no value to anyone. But there's another level, too, I think, which is that using the term bros to describe people who've killed and wounded many, spawning a mini-reign of terror, is a kind of linguistic way of taking the punch out of something inconceivably awful. Malone writes, "Dubbing the suspect bros was in large part gallows humor, a way of dealing with the surprise that these bombers appeared homegrown, a threat from inside our culture." Maybe it's also a way of puncturing that balloon of terror—or even insulting those who've committed awful acts, or regaining some semblance of power over them. It's like what happened when their Uncle Ruslan called them "losers." If we don't call them terrorists, they don't terrorize, maybe. If we don't give them the credit they clearly wanted, if they are instead just bros, maybe some part of their power dissipates, too. They might have bragged that they were the Boston bombers, but they surely didn't brag to anyone that they were losers, or, for that matter, bros.