You bring forward the typical NRA argument. It's not quite accurate though.

(I don't agree with the article OP linked. So it is not my point to argue in favour of it.)

Your argument is: A weapon is just a tool. A weapon does not kill. It's people that kill. Someone who created a weapon cannot be held responsible if someone else gets killed.

But what about the abundance of weapons? Or the ease of use? Or the accessibility of weapons in situations where you are emotionally unstable?

Maybe a better comparison would be the abundance of sugar in pretty much every type of food (from ketchup to some meat products) - instead of the spoon you used in your example. And the comparison becomes less ridiculous.

"But what about the abundance of weapons? Or the ease of use? Or the accessibility of weapons in situations where you are emotionally unstable?"

The designer (in this case Kalashnikov) had no control over the abundance of his design or who gets access to them. As for ease of use, if you want to learn how to use a firearm (or any skills for that matter) you can. Ease of use is not a deterrent.

I see your point but one could argue that someone who creates a weapon is - to some extent - responsible for what happens with it.

The big problem I see in the text that OP linked is that the author did not define what he means by good design. If you assume good design must incorporate a moral dimension, then I could easily follow his arguments. Personally, I would think an object could be brilliantly designed but completely immoral or unethical.

I mainly used the abundance argument to counter the either naive or malicious statement of "blaming the spoon for being fat". This is being used by gun nuts. It is not a fair comparison.