However, even the minimum coverage configuration and a few hundred ground station terminals would let SpaceX prove lower than 100 millisecond latency.

Marc has run many simulations of Starlink constellations across different orbital planes and with different concentrations of satellites and with and without laser links.

SpaceX can qualify for the pot of $1.6 billion per year over ten years in the low latency category for rural areas. They need to provide 25+ mbps down and 3 mbps up and be consistently under 100 ms latency. I would expect SpaceX to exceed those specs.