Li Yanan's confession in this passage is an admission that he is the mastermind, he is indeed the mastermind.
"Li Yanan, what are you saying?" Old Wang looked at Li Yanan with a face full of shock. His eyes were filled with nothing but disbelief: "Why would you do that, what are you trying to achieve?"
"Yeah, Li Yanan, you can't say such things lightly. Li Yanan, I'm telling you, don't be intimidated by him. Just because he tells you to say something doesn't mean it's true. Whether you did this or not, and if you're involved, you must think it over clearly before you speak. Let me tell you, you can eat the wrong meal, but you can't say the wrong thing, especially with a big case like this. A single mistake could be a death sentence, you must think it through."
If he confessed to these two crimes, there's no escaping the death penalty. This is a major case, it could implicate many people.