The Dems want full un-redacted memo because it covers many innocent people that were also targeted. This gives them more ammo for their speculation and more people to subpoena which stretches out their timeline to battle this.
There are many innocent people that were targeted in Muellers investigation. Leaks will only help the Dems point fingers, dragging these innocents through the mud. This serves the Dem timeline by asking for more subpoenas and stretching this out as long as they can. I see why Nunes is against this. It is clearly not good.