Mayu has part of your essay. The biggest thing, though, is that Setsuna loves Hatori and is so incredibly frustrated with him and everything else right now. He is honestly worried about him because while Hatori seems to hold so much faith in his connection to Akito, Setsuna can see that what he's doing because of it hurts him. And Setsuna cannot understand why Hatori still does. it. It's the sense of conflict that bothers Setsuna the most and makes him most adamant in telling Hatori to accept both his worlds. As Setsuna is starting to think Hatori is rejecting the camp one, he is getting more upset because not only does it ping Setsuna's latent fear of rejection, but it makes him feel that Hatori is trapping himself. So he is going to fight that, desperately.