It's not absinence teaching, it's not teaching them to use alternatives, it's teaching them to think for themselves, to make decisions and the consequences of those decisions.
But that gets back to the issue of 'morality' as you said (well said, by the way). If a parent sees 'abstinence' as 'moral' and wants that to be what their child learns, then what? That is wrong and not to be permitted because?
I hate to use emotional buzzwords in discussions like this, and I mean no harm, but can't think of a better way to say it - it is a purely liberal political viewpoint to believe that parents ought to be compelled (or schools) to teach children to 'think for themselves,' instead of teaching them not to engage in sexual activity. You grant the role of teaching morality to the parent, but then you strip it away from parents who would teach morals YOU don't approve of.
Thats what you are aiming for isn't it...bringing up your children to be well rounded responsible independent adults?
No, that's what liberals want parents to aim for. Parents may wish to raise children who respect their parents and obey them. That is seen by liberal as unacceptable, unreasonable, and freakish. It's sad.
But if parents are allowed to teach their children as they see fit, regarding sexual behavior (abstinence), that should take care of the 'responsible' part, and the schools, if they do their job and teach real education and not what tab A can fit into besides slot B, will take care of the 'well rounded' bit.
Liberals typically assume that everyone wants what they want - a child who is 'well rounded' and exposed to all concepts and ideas - including such things as the relative OKness of all sexual behaviors. But all parents do not want what liberals want. Some actually believe some forms of sexual behavior are wrong and not only don't want their children to be taught about them, but don't want their children to be told they're OK by the authority of the public school system.
I do not insist that public schools teach that homosexuality is wrong - I don't think that my beliefs trump those of parents who find it OK. But I am not granted the same consideration in return. Same for abstinence - I do not insist that schools teach abstinence, because I know it's a personal, family, moral issue and not fit for public school teaching. Again, I do not see the same consideration being granted in return.
What I see is a wholesale usurpation of the rights of parents by the state, which appears to be insistent upon teaching the 'right' and 'wrong' of sexual behavior. I was against it when the Bush Administration wanted 'abstinence' taught in schools, and I'm against the opposite. Neither belongs in the public school curriculum, IMHO.