Miranda and everyone on Cross Assault shouldn't have had to put up with Aris for sure. That said Miranda quitting as she did was insanely bad form. That is my only gripe with how she handled the situation. I do feel bad she folded under the pressure of the situation and Aris being a dick to her and everyone else on the show. She plays at Keystone though she isn't new to some colorful language.
Sometimes harassment/bullying can just become so overwhelming that the only thing you can do is just give up. The straw that breaks the camel's back, as it were.