"Sorry kiddo, i'm not a pedo"
"The height of consent is 5'5'', Igarashi."
He's not into her that way. I think the manga has made it pretty clear. He’s just not sexually attracted to her.
I don't think this manga has any erotic contemplations whatsoever.
The manga made it clear that he saw her as someone whose personality he'd like his hypothetical child to have... in Chapter 1. Even then, he reacted non-negatively to her proposing she instead be his wife.
Chapter 226 explicitly mirrors Chapter 1, but Chapter 226 also has Takeda explain how his view of her has changed since the beginning of their relationship.
That is to say, the manga's made it
unclear whether he'd reciprocate her feelings. This is alongside how he's regularly done things for Futaba that go beyond the scope of coworkers and potentially even friends.