She's just going to go ahead and make sure of that, crouching over the downed rebel to check for a pulse. She's slightly mollified when she finds one - and when she registers Seth's unsteadiness. Whatever he just did, it wasn't without consequence.

"What was that glow?" she asks as she straightens. 'Off-putting rift power' is starting to seem a likely explanation for why he was locked up. That doesn't necessarily justify throwing him in a cell - it's not as if he can help what the rift saddled him with - but she has her own safety (and that of the Beast) to consider, here.