Ok, this leads to more questions. First off, how would you know you could not beat him? Second, begging only happens on the red eye, so this is the first and only time you can do this because it will move the next time, right?
You know you can't beat hom because he's face up and you don't like what you see.
As for your other question, I don't understand what you mean--you're always allowed to go past the guardian to the red eye or beg for mercy even when the guardian is at the red eye. And the guardian only moves when someone defeats it and the result says it moves.