Fiery Body protects against mythic augmented fireball?

[Grimniir]

https://www.d20pfsrd.com/magic/all-spells/f/fiery-body/

This spell will protect against an augmented mythic fireball even if it normally ignores fire immunity?

Since you're not really immune to fire, you just get healed by it. It will kind of be like trying to damage a living creature with positive energy?

Or am I reading this completely wrong?

[KahnyaGnorc]

Being healed by an effect is not the same as being resistant or immune to it, and Mythic Fireball says nothing about healing. So, I don't see anything wrong with your reasoning.