The generator wasn't sped up beyond tolerances, the safety system that kept it synchronized with the wider grid deliberately brought it in out sync, like ramming a car engine into a much lower gear at high speed. The force has to go somewhere, and from the perspective of the generator the mass of the grid might as well be infinite.

As for better architectures, we're working on that, but industry is lethargic, lazy, and often organizationally dumb.

But there are limits to isolation. AC grid frequency and voltage and load flows are changing constantly, if normally by small degrees, and propagate at effectively the speed of light. It's impossible to have purely static immutable protection schemes for all but the most trivial of equipment.

Not to say it can't be a lot better.