Your mother must not have trusted many people in the late 60's.  Not only women, but also men had "hair that did not move".  
I get the point, but why pick on her hairstyle?  Surely, there are more substantive probs with this appointment.  If she were a highly intelligent, qualified candidate with that hairstyle, would you still point it out?
It would have helped, in my view, if you had included the explanation about rigid character.  That makes sense and puts the comment into context.