Why is Brahma requesting the Lord Varaha to kill Hiranyaksha before twilight hours when the Lord is omnipotent?

From Sundar Shyam Pr:

In SB 3.18.24 onwards, Why is Brahma requesting the Lord Varaha to kill Hiranyaksha before twilight hours? Is he not aware that Lord, being omni-potent, is beyond the rules of this world?