It's not about what you teach, it's about what they perceive. And if you aren't capable of teaching it in a manner which emphasizes that there is ALWAYS risk with sex, you're doing them a disservice.
I agree. However, doing anything badly is harmful. Done right, sex education has a positive effect, particularly on disease. That's been shown over and over.
And with kids, it doesn't matter. They're just too young (and remember, the women in Nigeria they're targeting are very, very young) don't have the ability to indulge in reckless sexual behavior, regardless of what you teach them or provide them with.
I'm sorry, I don't understand what you mean by "don't have the ability"?