Actually, this has nothing to do with the choices of charter schools. Most charters and traditional schools in the city would like to provide comprehensive sex education to students, but they are prohibited by law from doing so. (As a former biology teacher in New Orleans public schools before Katrina, I can attest the old system lacked comprehensive sex education, as well.)
I wrote a piece about this very issue last year when a local legislator was trying to get a law passed for a comprehensive sex education pilot program in New Orleans (it was defeated):
Please don’t unfairly accuse New Orleans’ charters for the absence of much-needed sex education programming in schools. Put the blame where it belongs: prudish, conservative legislators in Baton Rouge.