Looks like fairly typical DoD installation temporary lodging. I've stayed in many looking quite similar.

March ARB isn't closed. It just changed from an Air Force Base to an Air Reserve Base (ARB) when functions were realigned in the 90s and it moved under the Air Force Reserves. In fact the base lodging has continued to operate:

Air Force Inns

DoD lodging facilities definitely aren't known for their aesthetics or frequent remodeling, but are generally are clean, safe, and reasonably comfortable for what they are.

I doubt if they're using the hotel, since that's where the Reserve and National Guard guys stay when they're there. That pic shows what looks like a patio door, so it's probably not the Inn just from that. I.

The Washington Post:

To combat coronavirus, U.S. to deny entry to foreign nationals who recently visited China and quarantine returning Americans

Except now that family of 4 is being held for 14 days, not 3 days.

Oh happy day, with two young kids.

Maybe tomorrow they'll all hang out together and have a Super Bowl party. Might as well try to lighten things up when possible.

That may run contrary to the desire to make sure those staying at the base accommodations don’t mingle amongst each other and complicate the picture of who has been and has not been exposed to the Wuhan coronavirus.

FWIW, arriving into some parts of the US on CX — with plentiful CX first award space — from HKG involved nothing extraordinary from CBP and CDC at US airports of entry in recent days.

Curious to know what the Op thinks is the alternative? Let the virus spread unchecked and leave it up to individuals to sort themselves out?

Do you really see that that working out for the best?

Survival of the fittest by letting people deal with the good and bad of the natural world — infections included — has gotten humanity this far. But that’s not really a civilized alternative.

Serious question—how in the hell are they enforcing this? Because from my experience, they aren't.

Case in point: arrived at IAD today, cleared via GE as normal, and was never asked about my travel history to China in the last 14 days, either by the GE kiosk or by any airport or CBP personnel. Not even a temperature scanner like often seen at airports in Asia. Absent perhaps a direct Mainland China - US flight (or maybe single ticket Mainland China - XXX - US itinerary), it seems like nothing at all is being enforced. Does CBP/CDC not realize that people can fly China-EU-US itineraries (or infinite other permutations) on multiple tickets?

Or—shock—perhaps this really is just more theatre?

Because officially the ban hasn't taken effect yet. Here at ORD it starts at 1700 local today. We have one UA flight running late (1749) so we'll see what happens. MU is still scheduled for tomorrow, UA has one flight planned, HU I haven't seen any formal suspension. Tuesday UA intent is send 87 and 88 to ORD instead of EWR.

HKG-ORD has had nothing so far on this. Will it?

"Inn" here doesn't necessarily indicate that they only have basic hotel rooms - the AF lodging network is called "Air Force Inns" and typically the main facility on base is "such-and-such Inn" regardless of configuration. Base lodging often has a range of facilities from hotel/motel type rooms to multi-bedroom suites with kitchens for somewhat longer temporary stays. Just depends on the location. Patios and porches aren't uncommon.

It appears March Inn manages

The photos on the website seem to match the above news piece. Impossible to tell which of their 12 dozen+ buildings are being used with these folks. It could be that a specific building (or two) was set aside for the evacuees.

If there are too many DoD personnel needing lodging than what on-base space remains due to the evacuees, those DoD folks will simply stay in commercial lodging off base, as happens all the time when on-base lodging is full - quite routine.

In any case, the point is that the evacuees aren't staying in facilities that had been closed for nearly 20 years, but in currently operational buildings.

Correct and I'm not hearing anything that it will.

CX and BR still operating as normal.

I'm also hearing additional cities have been added over the 7, so this helps. EWR is one of them.

These people have already been in close proximity to each other during their flight from China.

Close proximity before or not, exposed to a then-contagious person before or not, encouraging closer physical mingling amongst the isolated/quarantined complicates matters in a way that is not good for clearing and clearing out people sooner than later without opening the door to possibly increasing the spread.