He listens carefully, nodding to signify to her that he's absorbing the information she offers him. It isn't unreasonable, but they've glossed over some significant things to impress the Guardians on their end as well.

"First of all, Thor is the only Asgardian we listen to around here. And that's only if we catch him on a sober day." Just to get that done because Loki is pretty small potatoes when compared to Thanos. He just wants attention and Tony refuses to give in if he can help it. "Before I became Iron Man, I made weapons. I didn't know it at the time -- or maybe I did, just not consciously -- but those weapons weren't staying with the soldiers on our side. A lot of them ended up in our enemy's hands. Countless innocent people died. Sergeant Barnes, like you, was taken and made to do unspeakable things. Scarlet Witch tortured us and killed her own people to prove a point once. Hulk has leveled entire cities. No one here is perfect, Gamora. But we all want the same thing." He hopes that rings truer than any platitudes he could give her about how her past transgressions don't matter.