the past is the past
The orphanage sequence in Trabia Garden is the one of the few parts of the game that isn't all about Squall and his problems. I joke a lot about FFVIII, but the truth is that most of the other characters got shafted in the name of Squall's endless manpain. I like his manpain (see: this goddamn website), but I do wish the other characters got some more development. Say what you will about FFXIII: all six playable characters were fully fleshed out through its narrative.
Anyway, wrong game. I do like the orphanage reveal a lot as a plot device, even if it makes this game even screwier than it already is. (Which is saying something, considering NORG. No, I'm still not over that.) Setting that aside, there are a few moments during the reveal that focus on Squall. The whole discussion starts when Rinoa asks if they have to fight, and Squall reflects on the prospect.
Rinoa: Maybe someone really smart can come up with a way, so we wouldn't have to fight anymore...
Squall: (What are you getting at...? If someone can come up with something, that'd be great... But no one's doing anything... They're all scared, uneasy. All they do is complain. They just pretend to be thinking. They criticize others, but in the end, they can't do anything, either. Rinoa, why all this, all of a sudden? What do you expect from me? I grew up in Garden. I'm a SeeD. Do you understand?)
Rinoa: Squall? You have to voice your feelings or else I won't understand.
Squall: You were...part of a resistance movement in Timber, right? Unlike others who were all talk, you took to your weapons and fought... And now you're saying all this? What happened to you?
I like to think that Squall's been quiet so long, and Rinoa has known him long enough, that her words here are a gentle prod to get him to talk. It's important to note here that action matters to Squall, while he continues to detest inaction, like I talked about way back here. It's not that he has an issue with diplomacy, per se; there's actually an optional conversation he can have with Mayor Dobe in FH on the subject following the Galbadian attack.
Squall: I wish you could be a little more understanding about us. We're not just a bunch of warmongers.
Mayor Dobe: Oh?
Squall: It's hard for me to explain... I wish...everything could be settled without resorting to violence... ...and there would be no need for battles. Like you've been preaching, it would be wonderful if things could be settled by discussion. The only problem with that is that it takes too much time. Especially if the others are not willing to listen. So I believe that fighting is inevitable at times. It's really sad. That's all I have to say. I hope you understand someday. I think the world needs both people like you and people like us. Thank you for all your help. Good bye.
The other versions of this scene amount to Squall giving up and not bothering to explain how he feels, concluding that their views are too far apart to be worth his time. I bring it up because I think it's quite relevant to his worldview, considering how he grew up.
Squall's been with Garden since he was 5. He never got adopted by anyone. I feel like his current age of 17 tends to overshadow the reality of his past: he's literally a child soldier. 17 feels close enough to adulthood for it to be "okay," but, uh, no. Fighting is all he knows, and sure, he knows it's sad, but Squall's a realist. This is just the way it is.
Throughout the game, whenever he encounters something he doesn't understand (like the Laguna dreams, or fucking NORG), Squall is quick to brush it aside and say it doesn't matter. His default reaction is to say "there’s no point in talking about it, we don’t understand it so we’d just be wasting our time." And he's the same way about the past.
He's not expecting what they'll find out at Edea's to make much of a difference, but he's willing to give it a shot. The present is what matters most to Squall, not the past. He only has one clear memory from the past, that of a little boy in the rain calling out for "sis," but that doesn't mean it's enough to push past his current troubles.
Likewise, the realities of his situation simply don't resonate with Squall. He might be aware on some distant level how much of his personality is a result of his childhood traumas, but that doesn't mean he's gonna do anything about it. He's got bigger problems right now.