He's demonstrated the concept with simple things like gun magazines. Theoretically, they're now out of reach of the government to control. Add in more time and better technology, and this concept is potentially a big deal for all manner of things. Interesting to think about at least.
Guns are just a current flash point that it's easy for people to get their heads around. But who knows what tomorrow will bring that governments will try to control only to find themselves unable to do so due to unskilled, cheaply available, distributed manufacturing capability?
We do have a number of extremely terrible incidents with resulting loss of life, many of these are very much preventable. My personal opinion, more laws restricting distribution will not prevent these, but better mental health services, safety tech and training will.
All this article really proves is that people who want to have a gun will have a gun. It might be extremely difficult, but those hell-bent on it will still succeed.