And if your minimum unit size is 1GW then you lose the flexibility to roll out the tech incrementally - the average modern coal plant requires 3 to 5 weeks per year for scheduled downtime for maintenance - so your first 1GW coal plant requires a bunch of other generation sources to cover demand during these periods.
Solar and batteries are the obvious solution for rural electrification: scaleable, cheaper/simpler to deploy - no large scale civil engineering involved, trivial to "operate", effective without the support of big transmission systems and it's possible to buy everything off-the-shelf.
Coal requires transport and extraction which are both pretty expensive processes.
In my home town of ~300 people, there was just a couple of houses which used coal for heating. That's because sourcing and transporting coal was quiet expensive.
Electric heating was much more common. Even the old expensive baseboard resistive heaters.
When we talk about extreme rural areas, what you end up finding is solar and batteries end up being the most preferred energy sources. This has been true for decades. That higher upfront cost is offset by not having to transport fuel.
It's why you'll find a lot of cabins in pretty remote locations are ultimately solar powered. This is long before the precipitous price drop of solar.
Last I checked mining and transporting coal required quite a lot of heavy industry equipment to do even vaguely economically.
If coal was cheaper and easier than other sources of energy, then the US would be building more coal power plants. But even with the Trump administration placing its weighty thumb on the scale to try and “save coal”. Coal plants are still being shutdown due to simple economics.
If existing plants can compete with renewables, to hard to understand how adding the cost of building new plants is going to change that.