This is indeed true. The contemporary "political correctness" in the German society could have been arranged by the Gestapo. We have a quite famous radio moderator here in south-west Germany. His name is "Elmi". He made jokes about the German railway that offered some spechial tickets to the eldery and changed the the slogan into "warme Wochen" (Weeks for fags). In our political correct "dictature" this was enough to kick him out of the Südwestfunk (A state-TV station I have to pay money for).
You are right that Germany is secular. Nevertheless it does not make sense for me that kids have to be encouraged to make a public commitment. Kids need a loving father and a loving mother who stand by their side when it comes to the question what to do or not. You may agree that if such issues are discussed in i.e. a small church, the members usually put much social pressue on those kids to do certain things no matter if they want to or not. A free society consists of the possibility to a free decision. I also agree that sex between 14-year olds is something that should be prevented, but I do not see such public pleges as a suitable mean.
The pledges make liars out of people.
The reason that teenage boys, in the article, have sex later than teenage girls is not male chastity (HA!), it's lack of opportunity. Girls can have sex whenever they want to, but boys? What does a pimply-faced 14 year old have to offer a girl? Not much. They want it - probably more than the girls - but they can't GET it, because the girls are not forthcoming (the girls are hitting it off with the upper-classmen).
So, we can dutifully trot children in and have them say pledges - and even have them MEAN it in all sincerity too - but when the situation presents itself, the offer is made, and the opportunity is there, those pledges get torn to pieces and thrown away. Oh, of course the children SAY that they have honored the pledge. Everyone still lies about sex all the time. (The notion that teenage sex is a "family" matter is ludicrous too. Teenagers do not tell their parents about sex. Quick, go quiz a teenager about masturbation. 100% of teenagers practice that particular "art", and 95% will deny it. Adults can influence children, but the notion that they can really STOP teenagers is, well, as naive now as it was in the days of Romeo and Juliet).