I agree that some things may be lawful but not expedient. However, we shouldn’t turn a question of poor exercise of discretion into a question of wrongdoing. The fact that something could have been handled differently doesn’t mean the way it was handled was inherently wrong.
The fact that the act is permissible within Nigerian corporate culture makes it contextually defensible, she’s not entirely wrong for calling him that. However, if the company specifically exempts the chairman from such conduct, then at that point, it becomes difficult to defend.