The Second Prince's silence did nothing to help him, but there was nothing he could do regardless.
The problem with mortal societies was the speed at which information traveled. The highest authorities of the world, such as the Emperor and his family, were held in an absolute position that turned all of their words into truth.
The citizens weren't aware of what was happening within the palace. The reputation they knew the Third Prince by was his own, not that which was newly established by the demonic seed controlling him.
They took his word as bond. It was even more damning when the evidence had been forged so perfectly. According to what the civilians knew, the investigator discovered that both the Emperor and his aide were killed two days ago, just before the Second Prince disappeared.