Let's be clear, AI is not making it easier.
Some imagined advancement of AI so great that it trivializes the kinds of attacks that nation states study is.
But you're applying that to the concept of the world as it exists now.
At that point the concept of just being able to infiltrate the power grid because it's designed in a way that's flawed to infiltration isn't a given.
The idea you can't have some tireless force actively adapting to every single imaginable exploit isn't a given.
The idea you can't have a tireless force trying to come up with attacks to in turn be mitigated isn't a given.
The idea we can't suddenly design massively independent renewable power supplies with thousands of sudden advancements isn't a given.
To be honest, the idea we can't disrupt zealotry isn't a given, just like people think it'll be used to "hack" society for the worse, why can't it be used to hack society or even the individual to be less likely to want to do that? I mean if it can take down power grids easily... how much more quickly can we move to a post scarcity environment?
This doomsday scenario requires not owning your mind to what the model could do except nefarious things... but the nefarious things you're describing would be literal miracles. The odds it can only preform miracles that are taking down power grids are pretty low.