Why can't the flood be real metis....
Because as told, it violates natural law.
And because all the evidence of reality doesn't support it.
And because the few testable claims it makes, fail when tested.
As told, it definatly, certaintly, demonstrably did not happen.
Unless you allow for magic to occur, off course. But if one gets to allow for magic, then literally any and all claims can be "supported" by invoking magic. So invoking magic is hardly a rational justification.
You don't think God can flood the world to undo what the demon angels did back then?
I'm sure a being that is all-powerfull can do anything it pleases, being all-powerfull and all.
I guess if "all powerfull" also means "able to do magic", then sure, I guess such a being would capable of triggering a physically impossible phenomenon and then use its magical powers to "reset" the world in such a way so that it looks as if no flood ever occured.
But that kind of logic also supports Last Thursdayism, which again isn't that rational.
Jesus refers to the flood as a real event and so does Peter.
So?
They both relate it to the future. Who are we to question the son of God and the Apostle Peter?
Thinking humans who are reading stories from the iron age?
Just as surely as God brought the flood in Noah's day to bring the events of that time to a halt....so he will bring an end to this rot once and for all....at a time when are not expecting it. (Matthew 24:37-39; 42-44)
So you believe religiously.