I didn't see the episode, but it's the interwebs.  Why should it stop me from commenting on it?

SPOILERS (Book 5)

One way for them to have Rosen survive without revealing some kind of latent Alpha ability, would be the several powerful drugs he was carrying at the time of the photostim.  Rosen on Parish's ability to heal, when he's thinking it through outside the hospital:

One way for them to have Rosen survive without revealing some kind of latent Alpha ability, would be the several powerful drugs he was carrying at the time of the photostim.  Rosen on Parish's ability to heal, when he's thinking it through outside the hospital: