Re: Kirk and the Prime Directive.
That's supposition. What isn't supposition is the fact that Vaal didn't build itself, the people of that world created it for their own reasons. In destroying Vaal the Federation (through Kirk) created a entire planet of people, perhaps many millions spread all over that world, who now were actual primitives, and defenseless.
This is all supposition as well. We have no idea about planetary population nor do we have any idea who built Vaal.
"I had no idea you were so... formidable. " - Anan 7 to James T. Kirk, A Taste of Armageddon