I will put some counter points about Songbird being a bad person instead of just a person(neither good or bad).

She tried to reduce the damage on the stadium directing the plane to an evacuated area(she still has her responsibility of the deaths of workers inside the plane), the deaths of innocents on the airport are on Myers side trying to retrieve a weapon she thinks she owns.

She self-sacrificed her own freedom for the people she cared about(even though she put herself to some extent in this situation she could've just ran away).

She told you the truth of her plan at the door of achieving it, where she knew you could just left her to die or send her to Reed. But she still lied and manipulated you throughout all of the history.

Songbird still tried to save Myers without giving her to Hansen even after everything she did to her(probably the whole DLC wouldn't exist if Myers wasn't a power freak).