"I am afraid your assertion that Setsuna is not a disturbing character is... canonically incorrect"
canonically incorrect
Don't even go there. I'll repeat as it seems you're slow: Canon is canon. It's because you don't get it. Allow me to enlighten you.
1. Setsuna commits several acts of murder and terrorism throughout the entire shows under the guise of "fighting for a better world";
Yes, but that doesn't mean that he likes it. It's only because of the fact that he only knows how to fight that he uses this method to bring peace to the world. He said that himself. It's his only way and he wants to believe in him, and his allies, that they can bring peace to the world by fighting.
2. Hallucinates gruesome explosions of corpses in front of him to no affect whatsoever;
They're not hallucinations. They're flashbacks. They're what he always see in the past. When that particular thing happened, he remains calm and pensive. If one is experiencing sypthoms of hallucinations, they wouldn't be calm and pensive. They would be panicked. Like what Allelujah, Soma/Marie, and Louise is experiencing.
3. Joins a terrorist organization not once, but twice;
As I've said, it's his only way of reaching out for peace. Fighting. He fights to be able to find a way to redeem himself, not for the past, but for the future. He canonically said this to Lyle Dylandy.
4. Imposes his will on others (while hypocritically accusing others of doing the same);
He does not impose. When Saji said that he didn't want to fight, Setsuna didn't force him. What did he say? Instead, Setsuna said that he understood and that he knows that. Instead, he reached his hand out and he wanted to be the one to fight for Saji. And as Lyle Dylandy pointed it out: "You're awkward. Why didn't you just tell Saji straight that you'll fight for him?"
5. Kills people who could be considered allies, if they get in his way;
Do you even understand why Setsuna killed Anew? He killed her because 1) There was no other way. He didn't want to kill her, and he would've saved her, if only there was another way. 2) He shot her clearly because he felt that it wasn't her anymore. He couldn't explain it to Saji when questioned, but he said that, "Anew isn't there anymore." He didn't know because he wasn't aware that he's becoming an Innovator yet. He felt the actual brainwashing (via quantum brainwaves) which is why he knew Anew isn't herself anymore. There was only one choice in order to save Lyle, and he didn't hesitate. Why? Because he's still hurt about not being able to save Neil and the others. Imagine how he felt when Lyle was going to die.
6. Imposes his will on the world and is seen as "heroic" for it.
He was never seen heroic. It's stated over, and over again, in canon that no matter what victory they achieve: They will be never be acknowledged by the world. This is why they're always at space, never finding a home, never finding true happiness. This is why Marina cries for Setsuna.
With that, I'm pretty much done, as there's no real excuse to veer away from canon facts.
Re: another da
canonically incorrect
Don't even go there. I'll repeat as it seems you're slow: Canon is canon. It's because you don't get it. Allow me to enlighten you.
1. Setsuna commits several acts of murder and terrorism throughout the entire shows under the guise of "fighting for a better world";
Yes, but that doesn't mean that he likes it. It's only because of the fact that he only knows how to fight that he uses this method to bring peace to the world. He said that himself. It's his only way and he wants to believe in him, and his allies, that they can bring peace to the world by fighting.
2. Hallucinates gruesome explosions of corpses in front of him to no affect whatsoever;
They're not hallucinations. They're flashbacks. They're what he always see in the past. When that particular thing happened, he remains calm and pensive. If one is experiencing sypthoms of hallucinations, they wouldn't be calm and pensive. They would be panicked. Like what Allelujah, Soma/Marie, and Louise is experiencing.
3. Joins a terrorist organization not once, but twice;
As I've said, it's his only way of reaching out for peace. Fighting. He fights to be able to find a way to redeem himself, not for the past, but for the future. He canonically said this to Lyle Dylandy.
4. Imposes his will on others (while hypocritically accusing others of doing the same);
He does not impose. When Saji said that he didn't want to fight, Setsuna didn't force him. What did he say? Instead, Setsuna said that he understood and that he knows that. Instead, he reached his hand out and he wanted to be the one to fight for Saji. And as Lyle Dylandy pointed it out: "You're awkward. Why didn't you just tell Saji straight that you'll fight for him?"
5. Kills people who could be considered allies, if they get in his way;
Do you even understand why Setsuna killed Anew? He killed her because 1) There was no other way. He didn't want to kill her, and he would've saved her, if only there was another way. 2) He shot her clearly because he felt that it wasn't her anymore. He couldn't explain it to Saji when questioned, but he said that, "Anew isn't there anymore." He didn't know because he wasn't aware that he's becoming an Innovator yet. He felt the actual brainwashing (via quantum brainwaves) which is why he knew Anew isn't herself anymore. There was only one choice in order to save Lyle, and he didn't hesitate. Why? Because he's still hurt about not being able to save Neil and the others. Imagine how he felt when Lyle was going to die.
6. Imposes his will on the world and is seen as "heroic" for it.
He was never seen heroic. It's stated over, and over again, in canon that no matter what victory they achieve: They will be never be acknowledged by the world. This is why they're always at space, never finding a home, never finding true happiness. This is why Marina cries for Setsuna.
With that, I'm pretty much done, as there's no real excuse to veer away from canon facts.