Hostile interview process feedback-- what should I have done?
You said it was a joint appointment. Not because of the email but because of the lack of people at the Education department meeting-- I don't think you would have gotten the job no matter what you did.  

In future, you could have waited it out, but I don't think you harmed anything by leaving the process early.  It sounds like half the hiring people wanted you, but the other half didn't. The email was probably just a mistake. 

To sum up, you couldn't have done anything to change the people not showing up or the email mistake.  Sending nice emails to people you did meet with might improve your chances for a future appointment.