Harden does not have the luxury of not suiting up, wearing a fat suit or giving low effort. IMO he clearly opted in because his value in the free agent market is not what he thought it would be for an extension or long term deal. He turns 34 next month and needs to have a big season and postseason to secure his final bag.
If Philly doesn't trade him he will accept whatever role Nurse asks of him whether that is similar to his role last season or playing more off ball to let Maxey get his shine on. The latter probably behooves him in the long-term because that might be his role moving forward on his next deal.