If you are a state actor, it's not difficult to gather a couple of programmers from the "antivirus" and security field and build something that is hard to detect.
It would be impressive if it was the work of a teenager but it's not.
The SCADA stuff was novel and interesting though and goes above and beyond your average malware both in what it did and the idea to do it in the first place.
A really creative hack, so to speak. (or destructive? anti-destructive? shrug)
And just to reiterate. They built a rootkit that stealthily sabotaged an effort to build nuclear weapons in a way that just made it look like the people who were trying to do it were just incompetent...
You also somehow need access to the industrial grade target platform in some way shape or form which is not something a teenager has lying around in their room nor extensive knowledge about to this extent.
You can buy the Simatic PLCs they targeted on ebay for a few hundred bucks.
Industrial automation stuff like this is a common part of the "technical high school" curricula where I live. (of course only on the "press this button and then that happens" level)
Ha, generally true probably, but in my case as a teen I got my hands of a bunch of old industrial PLCs and built all kinds of interesting things in my room. :-) Ladder logic is how I got started programing, I didn't even have my own computer back then.
It would be impressive if it was the work of a teenager but it's not.