Why would a CME disrupt a single brand and model of aircraft, when the entire planet is covered in computers that almost never have bitflip issues when a CME rolls through every few months?
I would guess barely enough cable shielding paired with long enough paths along the aircraft so that the signals there would be more likely affected by EM induced currents.
I'm guessing EM shielding flaw or something electronic. See my comment on the Toyotas. It doesn't make sense from a raw probability perspective.