I believe the issue is low frequency magnetic fields induce near DC currents in longer electrical transmission lines and those currents saturate the magnetic cores of the transformers connected to them. When the transformer core saturates it looks like a sudden short causing large currents to flow burning out the transformers. If the transformers are de-energized before the low frequency currents saturate the transformers they are not damaged.
So the satellites providing a few minute warning allows the generators to be shutdown/disconnected from the distribution system saving the distribution system from the coming magnetic disturbance.
Transformers work on alternating currents, not DC. DC or near DC has no changing current, which does not create magnetic flux in the core, which does not create faults.
But saturating the core in a transformer does not cause faults anyways. It is just the limit of the core's ability to carry any additional magnetic flux. It is directly related to the maximum current that can pass through the transformer. When you over saturate, the transformer stops sending additional current, it is topped out. It does not fault due to saturation.
I am an electrical engineer, specialized in power systems. Your description is not a concern.
Generating voltage spikes in long line transmission lines is a concern, but the modern power system have voltage "shunts" to protect from surges, lightning strikes, etc.