A few things:
Visual separation: Any time visual separation is used in an area with multiple aircraft around, there is a possibility that the pilot involved will acquire the wrong aircraft. Like that’s never happened before? It doesn’t automatically make the pilot some kind of natural-born fool, “DEI hire”, or any other aspersive characterization. Given that if the helo crew had been looking at the right aircraft they presumably wouldn’t have hit it, it seems like that’s a good place to start. We’re human. It happens. Look for ways to improve procedures instead of beating up the pilot.
Altitude: From an ATC standpoint, nobody in their right mind is going to count on a displayed 100 foot altitude difference being enough to let targets merge. With 100 foot display resolution, 200 feet and 300 feet could be 249 feet and 251 feet in reality. These aircraft needed some daylight between horizontal positions, which is likely what the helo crew would have done if they saw the right jet coming, and what ATC was trying to do with the “pass behind” instruction after the conflict alert went off. As the jet was on a visual approach, their altitude was not constrained to anything in particular. A nominal 3 degree approach path would have had the jet at about 250 feet at the east bank of the river descending to 50 feet on the west side: whether the helo was at 150, 200, or 250 feet, lateral separation was needed. Based on the crew’s acceptance of visual, the controller thought this conflict was fixed, right up until it wasn’t. Focusing on altitude is a bit of a red herring: the needed solution was to not be in the same geographic place at the same time.
Tower staffing: it’s perfectly normal for various positions to be combined or decombined based on the judgement of the supervisor in charge about traffic levels, the experience of the controllers on duty, weather conditions, training in progress, etc, etc. Having positions split has its own overhead - there’s a coordination workload when split that isn’t there when working combined. Having HC/LC combined 45 minutes before the “normal” HC closing time doesn’t stun me at all. Assuming that there was some staffing deficiency affecting this case is premature at best. Let the investigation evaluate that in the context of this accident - which in no way negates concern about overall staffing issues in the ATC system.
“Military training flight!” - Yes, doing exactly the same thing as any other helicopter following published helicopter route 1 to route 4. Would there be less consternation if this had involved some civil operator following the existing-for-decades route structure? “Should these helicopter routes be where they are?” is a perfectly reasonable discussion to have, but the military nature of this particular operation seems irrelevant.
Trump attributed his DEI comments on the accident to “common sense”, or (loosely translated) “I’m making it up.” I eagerly await his analysis of the Philadelphia Lear crash. Should save NTSB a lot of time and money looking at facts and evidence.