That is the minimum possible resolution* (hence the lower bound on the diameter). Atmospheric stuff will make it worse and be variable from day to day (and depends on the length of the exposure, which would be a bigger problem looking at stars than the earth). I think that is around 2 microradians for astronomical telescopes.

*there are tricks to get super-resolution, but ignore that stuff.

Lockheed famously hires a lot of adaptive optics people for "god knows what."

I think the answer is obvious now.

I want to add that usa-224 flies at a remarkably high altitude for a spy sat, and certainly higher than previous gen sats with perigees below 250km

From the wiki article:

orbital altitude of 250 km corresponds to a ground sample distance of 0.06 m (6 cm, 2.4 inches). Operational resolution should be worse due to effects of the atmospheric turbulence.[34] Astronomer Clifford Stoll estimates that such a telescope could resolve up to "a couple inches. Not quite good enough to recognize a face"