From the article:

“As we have said many times before, we have never built a backdoor or master key to any of our products or services and we never will,” Apple said

That fits my definition on backdoor. Not offering encryption so that gov can view the data is not the same as a backdoor. Gov said build a backdoor, Apple said FU, we wont do that, so we just aren't going to give you protection. It's a good move.

Thanks for sharing the article. It mentions in there that current users of ADP will have some time before requiring it to be turned off. I suppose that gives them time to backup whatever they have before it is purged or decrypted.