He certainly does not treat his teachers as college educated professionals. He has also shunned people in the community who have been long standing volunteers and supporters of First Coast High School.
The worst part of all this for the teachers is when he and his Vice Principal, Ms Townsend, started handing out egregious evaluations after only being a First Coast for a little over 2 months. The Union, and DCPS district staff said you can contest the process of the CAST evaluation, but not the ratings. He knew this and even stated it in the faculty meetings as he basically used the CAST evaluation as his big stick to fire anyone who deviated from his mandates. He would tie everything back to particular domain in the evaluation. The correlations were tenuous at best, and his use of the CAST evaluation demonstrated a serious flaw. If you can only contest the process and not the ratings, that creates a serious lack of Due Process. You can get an administrator who has issues and as long as that person does everything in a timely fashion, they can rate you anyway they want and you can not question their validity. That is what happened last year, and that is why so many teachers are so unhappy. They were completely devalued and they could not do a thing about it.
I have read your examples of bullying, and have one that is particularly unprofessional. He told the teachers in a faculty meeting that he expects his teachers to get to school early. I can respect having high expectations and rewarding those who go above and beyond. However, that was not Brennan's intention. He told the teachers that he would pull the sign in sheets at 7am and make note of who had not signed in yet. One problem...teacher sign in is 7:05am. Not a big deal unless you're running around like a crazy person dropping off your own children at daycare and rushing to get to work. Many people complained to the Union (and this is why Unions are still relevant). Brennan was told he could not pull the sign in sheet early. This made him angry, so at the next Faculty Meeting he let everyone know, and I quote..."if you want to live by that contract, I'll bury you in that contract". He bragged about how most people have not really read their contract, but he knew like the back of his hand.
I'm no lawyer, but I did stay in a Holiday Inn express last night, and I know there has to be an ethics violation when you threaten reprisal for taking contract violations to your Union. I can not believe that the Duval County School Board is going to tie their horse to this sinking ship and not support their teachers. This is the same staff who made First Coast an 'A' school before the good doctor got there (and by 'good', I mean 'horrible').