And I wouldn’t expect them to be training in them in a busy commercial airspace. But that’s just what I’d expect - not based on anything else.
Also as defrost said, nobody can know right now if they were actually in-use at the time of the incident. We have to wait for cockpit voice recordings.
Anyway, it's not really significant, though. I think Secretary Hegseth mentioned it because a portion of the public will equate "flying with night vision" to "flying in daylight" (even though it's not even close), so the DoD was taking all appropriate measures to be safe. Or he was just told that the crew was doing a "goggle reset" flight (because crew members need to log at least one hour of flight time with goggles every 60 days to stay current), and he jumped to a conclusion.
If the system can’t be safely designed with a safe margin of error then it is too dangerous.
There are alternative ways and locations to train.
If there’s a nat sec issue have the planes hold.
Whether the system (i.e. separating rotary-wing and fixed-wing traffic there) can be more safely designed is a question for the FAA. The military aircraft are simply abiding by FAA rules for that airspace. Many more civilian helicopters are doing the same thing.