It's interesting that Ryusui and Tsukasa both give up their long-presumed spots on the rocket to other people, with such wildly different tones and tenors and needs.
Tsukasa realized Kohaku was better than he was for the mission and made the decision almost immediately. He did one more quick test to verify, and that was a done deal. Kohaku is not quite yet who he is in combat, but she has other advantages that make her a better choice for the moon mission, and he is pleased by that.
Ryusui realized Stanley was better for the mission than he was, knew in his heart the decision was made, but then has to approach it in metaphor to Senku and pose it as a question instead of as a decision. As straightforward as Ryusui is, he just couldn't be about this. Stanley has advantages he does not have, and he is miserable about it (but strong enough to do it anyway).
And they've always been such oppositional characters in so many ways. Tsukasa has always been very anti-capitalist and owning things, and Ryusui is the Stone World's first capitalist who wants to own everything. And they have clearly come to terms with each other, and Tsukasa is not bothered once he understands Ryusui's approach, and Ryusui is not bothered because he wants Tsukasa anyway.
They made the same decision here, and went about it in such different ways, and it's a really interesting reflection of the way their characters have been the whole time. They both want everyone to have everything they need and want, and have very different ways of going about it.
Meanwhile Senku just went, I am going. Get out of here. I'm getting on that rocket.
