That's an interesting point. As you said, that's not all there is to it—after all, he was in prison for attempting a coup. However, your hypothesis that he got more radical over the duration of his sentence sounds plausible to me. If you're stuck with your own thoughts and nothing to occupy your mind with, you create your own echo chamber in your mind. That's part of the reason why I'm all for rehabilitation of prisoners.
That looks tasty! How do you make that?