If you are using massive amounts of nuclear power on your grid it doesn't matter.
TANSTAAFL. It does. Nuclear fuel is not renewable, and is heavily controlled by the government. Further, nuclear power is not a solution for these twits since they are afraid of a 'Hiroshima' in their community (which just demonstrates how little know about nuclear fuel!). The SDTC is shutting down it's last nuclear power plant in 2024. The SDTC is importing almost all their power now from the WRIC.
Solar and / or wind could be used too as the manufacturing process can be intermittent to some degree.
Remember, these are the most expensive methods of producing power, watt for watt. You have to transmit it to the hydrogen manufacturing plants too. That's a lotta hydrogen you're talking about there!
Hydrogen today is made by fracturing a hydrocarbon, leaving CO2 as a result. Very little of it is electrolyzed.
Wasting tremendous amounts of power like this to manufacture hydrogen isn't going to work. You are just trying to justify wasting energy. This is wasting even more energy than just using EVs require.
It also has the same problems of charging large numbers of EVs. Generating sufficient power AND transmitting it to where it is needed. You already are aware that electrical power isn't stored. It is generated on demand to the changing loads second by second.
You are already aware what happens when a transmission line that's overloaded sags (until somewhere it eventually touches a tree and trips out).
You are already aware what happens to 2nd and 3rd level relay stations when a transmission trips out like this.
This is how grids collapse.
If operators are fast enough and on the ball, they will shed load before it gets too far. No one wants a blackstart.