What he claims was his frame of mind is not relevant; it's what a reasonable person would be thinking/fearing at the time.
The FL Self Defense law states if a person reasonably believes. IOW their state of mind. They get to say what they believed at the time, not us. On hearing what a person believed and the circumstances of the time the jury gets to say if his belief was reasonable or not.
We don’t know what he was going thru at that moment. He could have been momentarily paralyzed in the legs from the impact; the attacker could have said “what, you shoot me, I’ll fkn kill you anyways right now”. Since you don’t know you can’t say if he was reasonable or not in making the decision to shoot.