Simply because a program teaches all methods of birth control (including abstinence) doesn't mean it's some diabolical scheme. The ACLU is trying to pressure these school districts to actually educate their students about all the available methods. Knowing teenage hormones, as I'd expect you do, it's very difficult to keep teenagers from doing things that they probably shouldn't do. Abstinence-only doesn't work, because it defies human nature.
Now, of course my complete sex-ed class in the Soviet Republic of Washington reiterated constantly that abstinence was the only sure method of preventing STDs and pregnancy. But they also taught us about contraceptives in case we weren't going to live up to that.
Abstinence-only is a great way to go, but not every teenager can do that. You can't leave them in the dark about protecting themselves just because you don't believe in contraceptives. That's like handing a kid and his friend a loaded gun, and walking out of the room, wondering what they'll do with it.