Every female member of his family that is of age is within his "strike zone". Why would his nieces be any different? We know he is fine with meeting random girls and trying to flirt with them (teachers daughter) so as long as he thinks they are hot (considering the family genes they are hot
) why would he not go after them? Unless baibai says his sister kids were off limits then it's safe to assume he would have gone after them if they were of age ofc which is why I asked if the amount of time had been cleared up I don't think he would go after them if they were ultra illegal.
Even if he for some reason wouldn't go after them all it takes is the sisters to think that the brother is still up to his old tricks (or they learned about him frequently getting prostitutes, they learned that he wore stained wife beater)
Did you grow up in a household with 3 girls 2 of which have breasts multiple times the size of their head? Not even considering the mom being drunk a good portion of the time and "harder to wake up" if you catch my (vn trope) drift.
I can't think of any in story reason, to me it would only be for the player to think "wow I saved this girl even more than i thought she better be thankful!" It's not like you can even get scenes with them because that would require them being in the bad future (where they don't like MC)