Steve doesn't have any issue being loomed over. He accommodates for his position on the floor by tilting his head back so he can continue to look Zerxus in the face, but that is about the extent of it. His hands even stay resting loosely on the floor.

If he'd noticed they were actually arguing he'd have crossed them over his chest. He probably wouldn't be sitting down, either.

(Yeah, this isn't an argument for him, at least not yet.)

"To stop mattering? It doesn't." It's a really confident statement, actually. "A guy who's got the stupidest bright idea I've ever heard because of his own trauma, but is doing it with sincere intent of protecting people doesn't get treated the same as somebody pushing it with every intention of killing millions in order to control them. Same consequences, either way, but different response. I don't trust guy one's judgement now. I'm gonna adjust how I treat him, what I let him know and how much damage he can do. Guy two? I'm going to do everything in my power to end."

A pause, then just: "It never stops mattering."