Voted for 1: Because he wants his own child from Nidhi.
Deep in his heart, he wants to have someone with his own blood & flesh. Khushi of course can give him experience of becoming a father but the joy of being a father of own biological child is incomparable to that of becoming a foster father - my pov only - He doesnt want himself and Nidhi to end up as foster parents only, that's why he is skeptical about adopting khushi.