We aren't talking about the earth being blown off course though, just that there is a large amount of energy that was previously unaccounted for and that this energy is large enough to trigger an earth quake at vulnerable parts.
Do the back-of-the-envelope computation of how much energy reaches Earth from a coronal mass ejection and see how well your idea holds up. (a typical flare is 10^16 grams of matter moving at about 450 km/sec)
CMEs reaching earth likely account for a mere fraction of the energy flowing through the global electric circuit at any moment.
Moreover, your suggestion seems to indicate that you’re only considering kinetic energy, which would be a very myopic and reductionist take on these matters.
