She was not a plot point. She was a caricature of Bush' Sec. of State Condi Rice. Just like Vic is Dubya, and Dakota Bob is Cheney.
Hughie redeems himself by saving Annie from Butcher or perhaps killing Butcher after Butcher takes out Annie.
It turns out that Mallory recruited MM to be a fail-safe to take out Butcher should he ever prove to be..."unreliable". Things don't go as Mallory planned, though, and we have a reprise of the full page "Noir carrying HL torso" scene, except it's MM carrying Butcher's drunk body out of a bar and to a cab.
Or The Female, at Frenchie's word, might be the failsafe! (I never did buy his origin story)
Re-reading issue 64, there are two items begging elaboration-
1. Butcher's call with Maynor mentions some guy not wanting to fly to DC that night. Who?
2. In HL's conversation with Stilwell, Stilwell refers to "miserable specied"; i.e. humans. What does that mean? Aliens? Or is Stilwell supposed to be an attempt at a higher order species? Could be, as his dad was a VAC big shot, right?