When you or I have them, they’re called “assault weapons”, and they’re made for nothing but killing large numbers of people rapidly, and totally useless for self-defense besides.
When law enforcement officers have them, they’re called “patrol rifles”, and they’re the best tool for protecting innocent citizens from violent criminals.
When the government orders 7,000 of them, they’re called “personal defense weapons”, and the DHS wants them because they are “suitable for self-defense in close quarters.”
Which is it? Are they only made for killing lots of people rapidly, or “suitable for self-defense in close quarters”? If they’re only good for rapid indiscriminate killing, why would cops and DHS agents need them? And if they have a legit self-defense function, why should they be banned for civilian use? The Federal government seems to think that these kinds of rifles are ideal for personal protection, otherwise they’d be ordering something else to fit the “personal defense” role. They can, after all, order whatever they want.
(And the versions ordered by the DHS are fully automatic machine guns, unlike the semi-automatic rifles available to Joe and Jane Citizen.)