People in statues don't take damage, the statue does. These four variables lock in the victims vitals so they don't incur any additional damage while in the statue. This is mostly to prevent damage that wouldn't make sense to be happening to something made out of stone (choking to death, dying in a fire or from overpressure). It's also there to avoid a bug with atmos in recursively stored mobs [described here https://github.com/tgstation/-tg-station/pull/973#pullrequestreviewcomment-5299387].

Note this doesn't HEAL any damage, it mearly holds them at the values they had when the spell was cast