> And in an innovative twist, the battery site can also provide short-circuit current in response to a fault, just like conventional power generators.
Sure. But, how much? The turbine at a nuclear/coal/CH4 power plant can handle upward of 10x the rated current for several cycles. The amount of fault current that synchronous machines can provide will always run circles around solid state solutions. This capability is essential for stability in downstream fault scenarios.
You can't really "saturate" a synchronous machine in the same way you can a farm of solid state electronics. Certainly, the 1GW turbine will eventually fail from an overcurrent situation, but it's going to last way longer than a semiconductor junction in the same situation.