"Dark Lightning"?

I'd never hear of this before:

Unknown to [Benjamin] Franklin but now clear to a growing roster of lightning researchers and astronomers is that along with bright thunderbolts, thunderstorms unleash sprays of X-rays and even intense bursts of gamma rays, a form of radiation normally associated with such cosmic spectacles as collapsing stars. The radiation in these invisible blasts can carry a million times as much energy as the radiation in visible lightning, but that energy dissipates quickly in all directions rather than remaining in a stiletto-like lightning bolt. ... Unlike with regular lightning, though, people struck by dark lightning, most likely while flying in an airplane, would not get hurt. But according to [lightning researcher Joseph] Dwyer’s calculations, they might receive in an instant the maximum safe lifetime dose of ionizing radiation — the kind that wreaks the most havoc on the human body.

By "not get hurt", I imagine the reporter means that a person struck by dark lightning would not be crispy crittered. Yet getting a lifetime's dose (or more) of ionizing radiation does not seem like a good thing. Maybe better than the alternative.