I don't see much wrong with the blog article, but I disagree with the OP about it being a poke in eye for copper slip users.
First, it says that threadlock is as effective an anti-sieze as copper slip, which is also my understanding. Second it concludes that if you have a big concern about bolts coming loose, you might as well use medium-strength threadlock rather than copper slip, which makes sense.
Personally I don't have experience of bolts working loose if I torque them properly, but I do have experience of weak threadlocked bolts getting rounded and needing to be drilled out. That's why I use copper slip instead of threadlock. There's nothing in the blog to invalidate this.