Jon is suicidal in a mostly theoretical manner. He chooses to keep living, despite knowing he is becoming a monster, he has regrets once he is actually down in the Coffin, and he says he doesn't know when Martin asks him if he would have told Melanie and Basira that his death would free them. Jon believes he doesn't deserve to live. Jon also wants to live. It's all caused by the Mr Spider incident. Jon feels so much guilt and shame about it because he knows he was the one who was supposed to die. He also probably feels guilt and shame because a part of him was relieved it wasn't him, it was his bully, instead. Jon has lived with this guilt for over 20 years, he has practice in choosing to live in spite of believing he doesn't deserve to.

Mag 200 is unique in that Jon actively chooses death. Even before Martin, he had already chosen to die: his plan was to starve the fears and to starve the fears means a certain death to him. And then he chooses a quicker death (I think he changed his mind top easily but this post isn't about it) for a chance to save Martin. What's notable about it is that Jon doesn't have an opportunity to change his mind and not go through it, like gouging his eyes out, or regret it, like with coffin. I do think Jon having a moment of hesitation in the middle, when Martin is about to kill him, before forcing himself to not resist, would be really good. Alas, Jon doesn't have that moment of hesitation. He is so eager to die for a chance to save Martin he pushes down his own fear of death and hatred of Web, playing into her hands once more.