I think the Mateo route is funny because the game specifically warns you what will happen and gives you ample time and opportunity to stop him. If he diddles your daughter, it's because you actively let it happen. You can even play a route where you catch him in the act and beat the shit out of him. I'm as anti-NTR as they come, but I think him being a molester and getting caught (and beaten to death by MC) would be a good lead into her loving on daddy's dick.
Besides, it's not NTR IMO because the MC isn't in a relationship with either daughter. Plus MC diddles the neighbor twins and his best friend's daughter. He's really no better than Mateo.