The very BEST managers to work under are the ones who see a problem, pull you aside to discuss it privately right then and there, and then let it go.
Hanging a problem over an employee's head, talking about the employee behind their back (conversations about an employee between managers should always be behind CLOSED doors), and not making expectations and instructions explicitly clear are all terribly ineffective management styles and can create a tense, unstable and miserable working environment.
While I'm sorry your friend lost her job, I have to agree with PPs who have said it might be a blessing in disguise.