During Maximum Carnage, was Spider-Man wrong when he begged Firestar to stop her attack on Carnage?

I'm wondering if Spider-Man was wrong when he stopped Firestar's attack on Carnage. Especially considering the dangerousness of this enemy and the possibility that her attack might not have killed Kasady if she used her powers for the right amount of time to get rid of the Klyntar.

Wouldn't Firestar's actions actually just have destroyed the symbiote, if she waited a few moments longer until she stopped or would she really have killed Cletus Kasady too?

If he died, what would have been the cause of death? The loss of connection to the Klyntar or would his human body really have been cooked to death? How much protection did the symbiote gave Cletus body against the microwaves?

What exactly happened in and with Cletus body during this attack? And was Kasidy's life really in danger at this moment? Because when Spider-Man begged her to stop, he was very quickly on his feet again and as dangerous as before. Just a few moments after the ordeal.