Rong Yan was having a hard time cracking this, but he was not able to figure anything out at all.
The Emperor had to act with just, in front of the crowd, thus, he ordered to sentence Rong Yan and Gu Tianqing to prison first, before passing his judgment on the accusation, after
the investigation.
After all, Rong Yan was just a teenager. Although he grew up in the palace, he was no threat to anyone at all, so even if there were people who looked down on him, there was no one who wanted to trap him, because he was not worth the trouble.
Therefore, he had no experience in dealing with trouble. He was already in a state of panic when he knew that he had to bear with the accusations but he could not do anything to prove his innocence.
He was not brave enough too. So, when the guards came to bring him to prison, he could barely stand up and was dragged out from the hall.