Semirhage was evil and did not deserve ANY respect or dignity. She was only terrifying or intimidating to cowards, who let the fear of pain dissuade them from what is right or true. Rand's order to ont torture her, no matter how misguided his reasoning, was the best command he could have given on that subject, becaused it forced Cadsuane to go outside the box and do what hurt Semirhage worst. I wouldn't have needed all that time to think on it, and I bet Egwene would not have either (assuming she could remember her first trip to the Heart of the Stone in Tel'Aran'Rhiod.