My hunch is that it was indeed an overreaction from both the passenger and crew. The crew seats have no markings that they are for crew members. When you are on a long flight and there are clearly empty seats by the toilets, it's common for people to sit there. I've done it, I've seen many others do it. Why they don't have some sort of "reserved for crew" signage to place on the seats is beyond me, especially with how touchy they get over it. It's never just a simple, "hey, those seats are for crew, please don't sit there." It's always a frantic "THOSE SEATS ARE FOR CREW ONLY!"