Which kind of comes back to the whole in-game mechanics vs logic that was brought up in Shadow Archon's link earlier (the one about kilometre-tall Marines). Just because the game engine allows it doesn't mean it's canon. For instance, in SC1, a Dark Archon who Mind Controls an SCV can eventually produce an entire fleet of fully-crewed Battlecruisers. Lore-wise, this can't happen.
As for phototherapy, it's main effectiveness is seen in treating dermatological injuries. In other words, they're used for
flesh wounds.
