“I didn’t talk to him about behaviour. I talked to him about how to get the best out of his staff.”
He chose his words very carefully. I think you'll find that civil service practice with KNOWN bullies is not to confront them but to use mediation and encouragement (e.g. how to get the best out of your staff) to get them to alter their behaviour. In other words O'Donnell has "outed" Brown as a bully by his wording.
I wonder if civil service Human Resources Departmental codes of practice would verify this. If I had the time today, I'd endeavour to find out. Perhaps my readers can enlighten us.