Thinking about how Zhou Zishu is fundamentally different from everyone else in Qi Ye in that he doesn’t have to be there. Helian Yi and Jing Beiyuan are both very explicitly shown to be trapped by their birth and positions, and Yunxing at least is probably similar as a noble. Even Lu Shen is known for his academic prowess and would have to pick sides eventually. And Wuxi of course is an actual hostage who’s explicitly forced into his situation.
ZZS is just a random jianghu guy. Imperial politics are a trap, but unlike the others he chooses to trap himself. If he’d wanted he could have stayed in the jianghu forever - Jiuxiao at least would have been happier for it. but no. He’s too ambitious for that (and his name fits so well - yeah yeah the SHL couplet is cute and all but the name itself is really about the arrogant, ambitious, ruthless young man in Qi Ye).
The worst part is that he isn’t even wrong to be so arrogant. TYK ch37′s “the mountains and rivers of the nation stood testament to his contributions” (quoting from memory) is right! He achieved what he set out to do! But where did that leave him, as a person and not a tool of the state? To quote TYK quoting Wu Weiye, it’s an empty existence only fulfilled by dying.
So he does “die” at the start of TYK, the same way Beiyuan “dies” at the end of Qi Ye. Both of them get to die, and both of them get to be reborn. The difference is that Beiyuan, at his core, is still a nobleman. This is exactly what Beiyuan realizes at the end of TYK, that though ZZS is no longer Zhou-daren, he himself will always carry Nanning-wang inside him. No amount of wiping the slate clean can change the fact that he was born a prince. ZZS’s “pure state” on the other hand, is the ridiculous gremlin we see in TYK, in a way that is very much informed by his lack of inherited status and jianghu background.
That wild, self-assured jianghu arrogance allowed him to turn himself into a killing knife in the capital ( “a pair of bloody hands upon which rests the nation” if you will), but now that Zhou Zishu, leader of Tianchuang, is dead, it’s that same confidence which brings him to freedom, unconstrained by responsibilities and expectations in a way that Beiyuan and Wuxi can never achieve. He’s able to do so precisely because he’s the same dumbass who, voluntarily and with eyes wide open, sold his soul to put Helian Yi on the throne all those years ago.