What the heck is this? Did the author suddenly confuse Yang Kai with the main character from some other series? This is the danger of writing in drunken stupor. Since when did Yang Kai care about sins or authorities? He's a dude who regularly humiliates people who provoked him even a little bit too much. Yet he himself must never be humiliated, and he can afford it due to the main character plot armor. He has destroyed many a sect. He has killed more people than anyone can count. What sins? This Bright Moon wasn't his friend or family. The one thing he doesn't want to compromise are his friends and family. Star Boundary? He doesn't give a shit about it, aside from it being the current home for his friends and family. But he has been transporting them from one home to the next multiple times. Star Boundary is just the current one. He never respected authorities inherently either (aside from his parents). A great emperor? They have given him more trouble than benefit.
This is all totally out of character and doesn't belong to this series. Only the author's bottle of whisky, or whatever he prefers, knows why we need to suffer through this nonsense.