Nolan has how many decades of experience? Other viltrumites haven’t ever really been friends, but moreso allies. Plus Nolan was, iirc, always seemingly dissatisfied with how the viltrumite empire was being run, but obviously never felt like he would ever have the power to stop it. Then mark came along and he’d been writing these books with secrets to defeating the empire just in case something happened to him because it was a contingency for if he ever found himself at odds with the empire. Because that’s what a smart man would do. He’d plan for the eventuality that the empire did not have his best interests at heart.