https://www.thewrap.com/joker-direc...dnt-make-the-movie-to-push-buttons-exclusive/
Joker Director explains how he pitched movie to Phoenix:
" "We didn’t make the movie to push buttons,” Phillips told TheWrap’s Sharon Waxman in an interview last Friday about the filmmaking process. “I literally described to Joaquin at one point in those three months as like, ‘Look at this as a way to sneak a real movie in the studio system under the guise of a comic book film’. It wasn’t, ‘We want to glorify this behavior.’ It was literally like ‘Let’s make a real movie with a real budget and we’ll call it f–ing Joker’. That’s what it was. “
So yeah, these guys knew all along it was a "Joker in Name Only" pic and were just hijacking the name for brand recognition. Because to them nothing from a comic book can be made into a "Real" movie.