Q: Does the Librarian have the powers of the Necronomicon to move Creepers around?

A: No. The Librarian card states that it “Counts as the Necronomicon for purposes of Actions and Rules if the real Necronomicon isn’t on the table.” The power on the Necronomicon Keeper is not an Action or Rule, so the Librarian doesn’t get to do that stuff. Neither does he get to count as the Necronomicon for purposes of meeting Goal conditions, obviously.

There are only two Actions (Revelations of Azathoth, and The Yellow Sign) and one Rule (Miskatonic Studies) which mention the Necronomicon, and these are the cards for which the Librarian can stand in for the Necronomicon.