You say that it isn’t safe for an eight year old boy to be around in the new world when he was birthed in the new world and only stayed his entire life within the most difficult spots of the new world. He survived punk hazard, Dressrosa, doffy, big mom, Kaido, much more u can say about 99% of one piece characters.
Bane: Oh, you think darkness is your ally. But you merely adopted the dark; I was born in it, moulded by it
Momonosuke will be there in Raftel. The boy looked death in the face and defied it, just like Luffy and look where Luffy is now. Momonosuke is the only character out of the three potential strawhats (Momo, Carrot, Yama-ass) to get exposition, Raftel relevance, Pirate King lore relevance, and character development all at once. The puzzle is there, the pieces are connected and the picture is complete. A boy that knows nothing of the peaceful world and the “paradise” of the grand line can’t keep up in the new world? Well I guess than Ace and Luffy should have stayed at home, Doflamingo should have stayed at home, law should have gave up on moving forward. Luffy needs Momonosuke for the Fourth Road Poneglyph and Momonosuke needs Luffy to learn leadership. That is that. See you post Wano when the boy is on the ship