Mcgee did not care what the nuns thought.
The main reason he made this weird request was to make them back off and stop bothering him.
Mcgee would not stop them if they wanted to be the Virgin Mary.
But there was no way he could be the Virgin Mary himself.
If he wanted to save them, he would have to go against his will.
If he wanted to be firm in his beliefs, he would rather die than surrender. Then, he would have to pretend that he did not say anything.
By creating a dilemma, Mcgee would be able to relax if she knew she was in trouble and retreated.
Of course, if Irene chose to save the people, Mcgee would naturally keep his promise and help her.
"Okay, I promise you."
However, to Mcgee's surprise, Irene only thought for a few seconds before replying firmly.