What's the agenda of the article? What was it written for, and what are those reasons? Who is it to benefit? That article is simply that, an article. I got out of it that shot placement was the deciding factor. And I've spoken to bullet companies that make compressed metal core ammo (a compressed metal powder, non leaded), and they do not recommend them on game. They are designed to literally go "poof" when it hits something. Again, same questions from above??
I think that it must be taken in the context of an alternative or a choice to full copper ammunition when hunting in areas where lead is banned. I don't think that anyone can argue that cup and core bullets shed weight when they enter an animal, and that's a good thing. Bonded bullets like Nosler Partitions also shed weight, but at a lower rate. All copper projectiles shed almost no weight, and thus the permanent wound channel isn't always as large. No doubt copper works well in many situations. Nobody can argue that, but isn't it OK to have another choice in areas where lead is banned? I hope that doesn't ever happen in Texas where I mostly hunt. However, if I lived in California (God help me), I wouldn't want to be stuck with all copper bullets for every situation.
With regard to them going "poof", and not being recommended for hunting, I first found out about these projectiles from a video on YouTube of these guys killing Nilgai with this projectile with 223's; 30-06; and 300 Win Mag on the El Canelo Ranch. I won't link to it here but if you're interested you can find it easily on YouTube. They certainly work as advertised. Again, the context is an alternative to full copper when lead is not an option. That's all.