I think the left hand thing for treats has a dual purpose. One is fewer people are left handed and second it makes the dog think and make a decision they have been taught to implement.
The temperament of most Service Dogs would probably be more likely to bring them toward people rather than away. They are so imbedded with their "people duty".
One time (about 6 years ago) I left my Cali with someone for a few minutes while I ran to a vendor at a show to purchase some shampoo. While I was gone she heard some noises overhead in the gymnasium. She was not able to find me, which was very uncomfortable for her, but I arrived back at the scene where she had jumped down and herded about 20 people away from the area by barking and nipping a them away. One half of the gym ceiling collapsed sending 100+ people to the hospital. Those 20 thought she was great!!!!
They did mention that at the beginning they thought she was a bit of an aggressive BULLY
