An A/C consumes more energy when the temperature difference is higher, which is when it’s sunny outside. At those points in time, the grid is receiving a lot of solar power.
So just saying a grid has 10% solar is too simplistic. That grid probably has 30% solar during summer noon and 0% solar on a winter morning.
If your goal is to save emissions, your best bet is to get some solar panels if you can, run the A/C when the sun is shining. Have a well insulated house that acts as a thermal battery and turn the A/C off during the peaks of the duck curve.
A/C for cooling is one of those things that highly correlates with the availability of solar power.
So your assumption that they are running on coal is suspect.
Heatpumps running in the winter are a more pressing concern, since those are highly correlated with the unavailability of solar and therefore often run on coal or gas (unless wind or hydro is available)
Even so, burning gas in a power plant and then running a heat pump is more efficient than burning gas to warm a house.
I guess the rest of us will need to figure out living in a world where we have conquered lions, bears, the Black Death and famine, but not yet the stupidity of our fellow countrymen.