I apologize but perhaps I have misread your answer or you have misread my original question.
In the end I do not want a greeter asking for a password field. I would like the OS to boot directly into the UI with one of my logins without user interaction. This is important to me if I want to reboot the Raspberry remotely and have the LAMP server up and ready; the greeter in Ubuntu Mate 16.04 prevents me from doing this.
I apologize if my questions was originally unclear.