As you said, sex has consequences. And if it took him six years to realize this and do the math, he's already hooked. And as Jimmy Carter once said, "Life is unfair". So, since he was a bit slow on the uptake, child support, "father" status, all the stuff that is needed for public policy went into effect.
Men are morally responsible for where they place their seed...tricked or not.
This is especially true with underage women. Something about statutory rape really kind of erked me in law school, 'cause ya feel for the poor soul who looks at jail time because of a fake ID, she told me she was 18, she looked like she was 18, etc, but if she is 17, you're dead meat.
But like this thread, and your observation, you gotta be responsible, and sex has consequences. It's much more difficult to be convicted of a crime or falsely accused of being the father if you actually meet the parents of the significant other prior to consumating, or more discreet with whom you recon with....
Pookie & ME