Here is the catch. You cannot have a BDSM room without manager. Having a manager is what triggers it.
def strip_club_manager_bdsm_room_suggestion_requirement():
if not mc.business.event_triggers_dict.get("strip_club_has_bdsm_room", False):
if day >= (get_strip_club_foreclosed_last_action_day() + 15): # the event trigger after 15 days you have a manager
if not mc.business.event_triggers_dict.get("strip_club_bdsm_decision_day", None): # Not suggested yet
if __builtin__.len(stripclub_waitresses) > 0 and strip_club_get_manager():
There is no variant for building BDSM room without manager like with strippers and waiters. It's her plotline to suggest the room and discuss it with you. You must be having one already. Either you are unaware or the code considers someone as anyway. But there is an entire discussion with her before you can build the BDSM room.