Don't get it at all. My response is, 'So What?' So he did some legal work for Hannity. I don't care.
I wonder if Hannity has a way to sue over this obvious breach of confidentiality. It is hard to believe that this behavior will be tolerated in the legal profession. It would change everything if lawyer-client confidentiality is no longer applicable. Where is the ACLU?
It would probably not have been an issue or even a "gotcha" had Hannity been up front about his relationship with Cohen before he started railing against the raid on Cohen's office and other things related to the Mueller investigation that Sean has gone on a tirade about.
I believe the proper term that should have been used was "In the interest of full disclosure..."
That would have killed it right there and Sean could have gone on being Sean.
But he didn't do that and now he'll have to put on his big boy pants and endure the media feeding frenzy that has begun over this.