I guess treating him like a guy is the wrong way to put it, but he treats Natsuki in the stereotypical way one would treat a girl and it's clear that he doesn't fully see Natsuki as a guy, so he treats him differently than he would treat one of his male friends. I don't think that people should be treated differently based on their sex, but that's how the mc is treating Natsuki
What I meant to say here was that if I were in the same situation as the main character, I would also show my love for the person I like in that way regardless of their gender, I would treat them with care and affection which is the way some men treat women as if they wanted to show they can take care of them (something like that, English is not my first language xD )
It's cute but I wish mc would treat Natsuki more like a guy and didn't have this clear disconnect between his perceived version of Natsuki as a guy but not really and him when he isn't cross-dressing, it just makes his feelings seem disingenuous