And now, you are confusing the issues also. The point about residential solar is that, when all those A/C units kick in, so does the output of the solar systems. Moreover, that electricity doesn't have to be delivered over the grid. Residential solar has a greater impact than just the generation cost.
Utilities have a perverse incentive: since they generally operate both generation and end-user sales, with prices set through a regulatory body, these utility companies actually benefit when the base cost of generation increases. Solar threatens their profit and that's why utilities oppose it.
As for Hawaii, the story is clearly not finished there. Hawaii has some of the the highest electricity costs in the nation, so the opportunity for solar is greatest there.
Finally, the argument initially was about solar in general, not specifically rooftop solar. As I pointed out above, even if utility-grade solar offer the possibility to provide cheaper electricity than the alternatives, utility companies benefit from the status quo, and that is why solar has had such a small impact on US generation.
If it is financially viable for an oil state to use utility grade solar, it's financially viable for most southern states in the USA.