I know nothing of the politics at United but I read it as an impassioned plea to the flight crew to do their jobs professionally.
I read it as a plea to "straighten up and fly right even though we have failed to establish a positive safety culture and have allowed you to bust SOP's for years, failed to reign in the outlying cowboys, failed to empower the disciplined amongst you, and watched as human nature did it's thing and a large majority of you bowed to the pressure exerted to get the job done"