He has gone back upstairs to watch over the railing and stay out of the way, and at the mention of the radiation, he retrieves the radiation sponge from Ianto and then tosses it down to them.
The Tosh mistake makes him wince; it's so hard not to do that in these situations. "Luckily we've got a technology whiz, eh? When that swelling-- oh!"
He snaps and then waves his hands in a 'got a thought, got a thought, just gotta make it come together' matter. "Oh, this is crazy but-- Martha said when she was at the Pharm, they could tell she'd traveled in time and space because of the cellular mutation, how she was like super healthy, as if the background radiation had gone and made her body more efficient. And we humans aren't exactly designed for hurling through the Vortex, but Doctor-- people like yours, already in tune with it, regeneration-- what if maybe, just maybe, Jenny's system bounces back better than ever from this?"