Apparently the Left, meaning 'the system', is claiming that Cohen is not a real attorney with attorney/client confidentiality because he only has one client, President Trump. Why this make any difference, how they came to this conclusion has not been explained.
So then Cohen said, 'I have more than one client.' The court ordered him to release his client list and he blurted out 'Hannity'. That is how all of this came about.