It really can be felt that Nanashi is super comfortable with his manga's position. He gave this scene a whole chapter, with barely any dialogue, it's almost too much space to breathe.
It was directed in a way, that made everyone expect some kind of cheap interruption and postponement, but he just went for it instead. Really fits with their current vibe of being awkward and inexperienced, yet still pushing through to get closer and further their relationship. They are still like 2 tomatoes throughout, but they know they want it and are going for it. With that approach, this may need an official doujin within like 20 chapters.