Su Yu had killed Heavenly Seal King without any hesitation. Hesitation was not required for certain tasks. That was especially true when it involved traitors. There was no need to say more. There was also no need for lengthy trials. They had to be decisive about it and make use of humanity's joy due to the recent victory to distract everyone from the implications of his death.0

In many stories, most villains had ultimately died due to their habit of dragging things out. As far as Su Yu was concerned, an enemy should be removed as soon as possible. Giving an enemy the time to grow was the most idiotic thing one could do.2

Take the myriad races as an example. They could no longer do anything against him. But in the beginning, they could have sent someone strong enough to kill him and end his journey. Alas, they made the wrong choice. Then again, they had been sending Invincibles after him since he was a Skysoar. He could only say that he was too impressive to be killed.3

As for the matter concerning Heavenly Seal King, he had to get it done before anyone had the chance to plead for leniency on his behalf. Yes. That could really happen. After all, Ye Batian and those from Liu Family were already dead. Someone alive was worth more than the dead.1

As for his attempt...0