The thing to realize is that what we are experiencing is a fluke. The electric grid responds differently to equipment malfunctions depending on the precise operating conditions at that time. For someone to be able to know exactly how to hit us in a single spot at any given time and cause a cascade failure strikes me as highly unlikely. Not impossible but very unlikely. That would mean that th grid was operating with a single contingency. That is a big no no sombodies head should roll.
I wonder what amount of spinning reserves were on line prior to this event. I will bet that somebody scrimped on the reserves. It used to be that spinning reserves were 10% or the size of the largest single unit on the grid, whichever was larger.