I have never heard of a "rule" that says a girl doesn't allow her back to be to a Free Man or Free Woman. So I did a little research and, sure enough, found no such rule.
In fact, just the opposite . . . as shown below.
"Slave!" he called. He snapped his fingers at her, pointing to the planks of the wharf at his feet. She sped down the gangplank to kneel swiftly before him. I followed her. He lifted her to her feet and kissed her, and then made her turn her back to him.
Hunters of Gor Book 8 Page 69
"Bracelets," said the first instructrix.
Ellen turned her back to the first instructrix, and lifted her wrists a little, so that her bracelets might be checked.
Prize of Gor Book 27 Page 171
"What is it, Master? What is it?" called a slave to a passing guard, but then she cried out in fear, turned her back, crouched down, and covered her head with her hands and arms, and was struck several times with his switch.
"Curiosity," said the guard, "is not becoming in a kajira."
Swordsmen of Gor Book 29 Page 490
She then rose lightly, sinuously, before him, and, turning her back, left.
Beasts of Gor Book 12 Page 301
"Face away from me," said my keeper. I faced away. Another fellow waded by. "Stand still, draft beast," said my keeper.
Vagabonds of Gor Book 24 Page 134
"To all fours," said he, "and face away!"
I complied, frightened.
Witness of Gor Book 26 Page 712
"Master?" cried the slave, frightened.
"Turn about," he said. "Face away from me, kneeling. Put your head to the rug. Clasp your hands behind the back of your neck!"
"Stand," he said. "Face away from me. Put your head down. Cross your wrists behind your back."
Kur of Gor Book 28 Page 283
"Face away from me," said Cabot. "Place your hands behind your back."
Kur of Gor Book 28 Page 388
One may either face the slave or have them face away from one.
Swordsmen of Gor Book 29 Page 460
"Stand," he said, "face away from me, put your hands behind your back."
Conspirators of Gor Book 31 Page 656
"Face away," he said.
I turned away.
Plunder of Gor Book 34 Page 258
