I agree that a slave demonstrating disrespect is a serious matter, as shown in the first thee quotes I picked out . . .
"I am a slave, Master," she wept. Disrespect in a slave can be punishable by death.
Fighting Slave of Gor    Book 14    Page 108
"Yes, Master," I had said, struggling to my knees, the chain on my neck. I did not wish to be slain for disrespect.
Fighting Slave of Gor    Book 14    Page 305
In no way, either by word, tone of voice, act, expression, or attitude is one to show the least disrespect. The slightest suggestion of such a thing may result in severe and prolonged punishment. The woman is free, while one is a slave.
Conspirators of Gor    Book 31    Page 105
I am not quite sure I remember the disrespect the same as you, when it comes to defending the master.
These are three examples that came to my mind of where a slave did, in fact, defend the master:
His hand drew Talena's dagger from his belt, and, manacled as I was, I could not have prevented the blow.
Suddenly his eyes emitted a wordless scream, and I saw a bloody stump at the end of his arm. Talena had picked up his sword and struck off the hand that held the dagger. I released my grip. The officer shuddered convulsively on the grass and was dead. Talena, naked, still held the bloody sword, her eyes glassy with the horror of what she had done.
"Drop the sword," I commanded harshly, fearing it would occur to her to strike me with it. The girl dropped the weapon, sinking to her knees and covering her face with her hands.
Tarnsman of Gor    Book 1    Page 104
Now, discovered, Fish fought by my side, that we might, together, protect one another.
"Now, Slave," said I to Fish, "you should have stayed with the fleet."
"Be silent," said he, adding, "- Master."
I laughed.
I saw the boy, with a lightning thrust, flash four inches of steel through a body, returning to the on-guard position before the man realized he had been struck.
In fighting as we were, one did not use a deep thrust, that the blade might be more swiftly freed.
"You have learned your lessons well," said I, "Slave."
"Thank you, Master," said he. He dropped another man.
Raiders of Gor    Book 6    Page 287
Telima, wildly, her two hands on the sword, struck a man from behind in the neck and he fell away from the blade. Then she had lost the blade, as an invader struck it from her hand.
Raiders of Gor    Book 6    Page 297
Using 'disrespect' as a root word to search by, I found no reference to disrespect, in conjunction with defense of the master, even being shown, let alone as a bad thing.
Based on the examples I provided, I would say it's just the opposite.