Shang Long questioned the princess: "Princess Lianhua, please answer the court, did you find Ashen's question an attack on your honor? And if not, was your guard's action as per your wishes or did he act out of his own volition?"
This question was harmful to her either way.
If she were to reply with yes, then she'd have to justify how petty she was that she found a simple question of Ashen an attack on her honor. It'd also justify that she was weak and couldn't defend her honor herself.
If she were to reply with no, then that would mean that the old man acted out of his own volition and that Ashen was innocent and he was attacked without any fault.
Both options were going to her doom.
The first option would harm her reputation and also make her look like a fool who finds just anything an attack on her honor.