The Blood Red Star Moles that Zhu Bufan mentioned, and the elder who incessantly refers to himself as 'this seat', point squarely to the contemporary Family Head of the Zhu Family, Zhu Changshun.
Due to the shock to his mind, Zhu Yuheng did not carefully ponder Zhu Bufan's words. Had he been able to calm down, he would likely have easily spotted the flaws in Zhu Bufan's statements.
If it really was Zhu Changshun, then why would he constantly be referring to himself as 'this seat' in his conversations with Zhu Bufan?
The reason for Zhu Yuheng's shock is that Zhu Changshun is a person of low profile; in such a remote place as Nanli City, the only person who has seen him in person is Zhu Zichu, the Zhu Family's representative in Nanli City.
Zhu Bufan came to know of this through inquiring from his good friend, Zi Yu. However, Zhu Bufan's original intention in making inquiries was out of curiosity about what his heartless relatives looked like!