Well the Guardians pulses were knocking covy ships out of the sky and they have energy shielding. It was heavily implied that Infinity would have been stopped had it not fled, and it also possess powerful shielding. So yeah, barrier = emp protection sounds off especially if from a world where it was designed to ward of Ki.
And yeah.... halo 6 is gonna be a hard sell when it comes to how they plan on stopping her. She holds every conceivable edge :/