Question about children?

ok, so one of my friends has been going out w/ his girlfriend for about 2 years; being friends w/ him for over 7 years i know he was never really interested in having children. He seems to be serious enough with his girlfriend, and they've been talking about the topic, so he says- and she really doesn't want to be with him long-term if he's not interested in having kids; he's undecided as to whether he would seriously consider it but he's always said he hates kids and has no patience for them; he jokes about getting so angry that he just gets up and leaves his family and moves across the US, and even said, half-jokingly, he'd be afraid he would lock his kids in a closet if they misbehaved, just so he wouldn't have to deal with them; my question is, being his friend, should i advise him not to consider having kids just to stay in this relationship, since he doesn't seem keen on the idea? or am i reading too much into what he's saying?