Yeah it really makes no sense. Gotham City Sirens works so much better for the R rated girl gang flick they’re trying to make. Plus it has “Gotham” in the title which already increases its marketability. They could do a Birds of Prey movie after that with Batgirl as the headliner.
It’s like taking the concept of Suicide Squad, putting Nightwing on the team and calling the movie Titans.