Perhaps I'm overthinking this, but open source malware is absolutely not new. It's been around basically as long as the internet has (and I mean pre-www). You could even argue that it pre-exists the internet since phone phreakers were sharing "code" earlier than that.
That's true that malware source code was available in the open even before large scale Internet access. But no one made a fuss about licensing, "freedom", philosophy and the authors were mostly unknown.
Technically it was obfuscated, so not open source by definition.