They would have someone scream something out then get ejected from the courtroom.
they had coordinated attacks on him in the trial.
Maybe they didn’t realize there was something else that was supposed to happen. They broke the bond and then a blade was there, there was no way to know this meant a Spren died. Not even the screams would have told them that.
It was probably inconceivable to think that a spren could become a Deadeye.
It was only a few weeks, or even months or years later when deadeyes started to appear in the CR that they realized what was happening.