While there is some biological plausibility to that for young men, older men know their off spring stands a far better chance of not only surviving, but surviving far better if they, the men stick around.
Whereas young men are likeliest to die young defending the tribe as they are the fittest, agilest and strongest. This remained true when tribes transformed into countries, young men are still the premium defense resource. And of those young men, the high school football/hockey team have to be the best of the premium resource. They work well in a team, they are fit, fast and smart enough. Exactly the kind of kids you want defending us.
Young men's kids are needed by our nations because they will invariably be the next generation of cannon fodder. Society expends few resources on them. Their mother teaches them enough language that they can get by in society and they may get enough education to make them useful to the military forces. They also learn to buy a girl a few drinks, treat her especially well for an evening and then she will likely give herself to him with the promise of calling on her tomorrow, when in all likelihood she'll never see him again.
Young men will do pretty much anything to get laid, generally, and, unfortunately, some women will pretty much do anything to get love. I personally think it is better to be alone than be with the wrong person, now that I am older.
But I remember when I was young, I was unlikely to have been easily convinced of that. I couldn't wait to find love. The man who was the other half of me, who would complete me. Sex was a new concept. Enticing, the ultimate expression of love. A concept totally intoxicating to most young girls. Yet the reality is teenage boys the same age as the girl are utterly useless sexually. They are likely to cum upon entry and then if the girl is as unfortunate as Bristol Palin, she'll be forced by a self-serving mother to have a baby she doesn't want. I can't imagine Bristol got any pleasure from the blessed conception and nothing but years of humiliation afterwards. And despite the humiliation, Bristol is one of the lucky girls who has family that will help her take care of the kid. Many young girls will have to survive on their own without any help if they have been bludgeoned into believing abortion is bad. If they do have an abortion, they will possibly spend the rest of their life regretting it. Or, potentially worse, adoption, worrying whatever happened to their child.
If I could tell all teenage girls this one truth, I am sure it would bring down the numbers associated with teen pregnancy. Boys your own age suck so hard at sex and especially at love, its truly not worth being involved with them. He'll have all the fun and you'll have a life time of misery, probably. It really is better to wait until you are old enough to find an older guy. If teenage girls knew this simple fact, it would possibly cut down on the number of teenage pregnancies. But for some reason society has a vested interest in protecting the egos of men, no matter what age they are.
Or at least use contraception. But abstinence just doesn't work unless you know that the teenage guy is just gonna be really bad at it. Besides how likely will he be able to support you if you do get pregnant and keep the baby?
Older men know that they must stay with the mother, if their children are to prosper. Premium children have premium resources spent upon them. Look around, you see politicians, CEOs, lawyers, professionals, scientists, academics and business owners, in general, come from two parent households. If they did come from a single parent household, there would've been plenty of help and plenty of money. Lots of resources are spent on these kids.