Nanahara Takeshi made a decisive escape, compassion aside, and though he was willing to help, he wanted nothing to do with any romantic entanglements.
He wasn't the hard-hearted type, and after spending time with Naikawa Yoshino, he feared that a sentimental error might occur, forcing him to develop feelings. Wouldn't that mean he'd have to switch careers and become a fast-food restaurant owner?
Better to avoid that altogether. Doing good deeds was one thing, but getting personally involved was a recipe for trouble—harming oneself as well as others. Why bother?