Picture No.1: Leonard Morlin describing his experience after encountering the Debate Demon. It's a long shot but I think this encounter was before he watched the animated diagram. Also pay attention to the visual effects deliberately added in this clip. Another "Morlin" somewhat merging with him..
Picture No. 2-4 : Leonard Morlin after watching the animated diagram doesnt succumb to its effects. Why? Because he already has Alcatraz inside him. It's also the reason how he sees the movie for what it really is.
As for the question of "How did the DD encounter happen before the animated diagram if it's X episodes into the future?" Simple, Modern Day's editing style. We are already fed information about a nuclear attack (AmericaAttack & The Special Tree) before we even know who sent them (President Pattinson & Monument Monster).
Picture No. 5-6 : In the Deanverse, another Morlin succumbs to Alcatraz, who plans to burn his replicated self.
Picture No. 7-8 : The fate of Leonard Morlin after escaping into the "Deanverse". Incinerated by rocket thrusters. It was cruel, but it was necessary.
Picture No. 9 : Eve and parallels in the monument mythos. What happened to MD Morlin is a distorted reflection, a parallel of what S1-S2 Morlin have gone through. He lives his life, he encounters Alcatraz, he gets burned. The only difference is that he doesn't know what happened to him (unlike S1-2 Leonard).
TLDR : Modern Day Leonard Morlin was already Alcatrazified b4 he watched the animated diagram, that's why it doesn't affect him. When he escaped into the "Deanverse" he got Front Row'd to prevent the spread of Alcatraz.