I can't accept the creature being a coldly calculating, intelligent player. Sure, we may get the illusion of this when it "reasons" with our heroes in the briefing room - but that's what it is, an illusion of reasoning. The creature doesn't really know Swahili or look like Nancy Crater. But it does make its victims see, hear and apparently also feel whatever they want to see, hear and feel. Intelligent conversation should be no different from pleasing looks in that respect.
Our heroes want to hear McCoy plead for the creature in the scene. But only because they want him to play out that mandatory part so that they can proceed with the hunting down and killing. The very fact that the fake McCoy's fake argument is presented already dooms it to utter irrelevance, then.
The actions of the creature are consistent, then, even if appearing illogical. It's not a course of action for a creature aware of all the pertinent facts and planning ahead, that much we can easily tell. The actions will not secure a supply of salt for the medium term future, nor give the creature a ride to a tastier environment. They only provide immediate gratification. But they do that in a consistent manner.
Now, are the heroes facing a mindless beast? Or perhaps a deranged survivor of the civilization that created the buildings now in ruins? Or an extra-M-113ian monster from far away that perhaps but not necessarily played a role in the collapse of the civilization? The facts of the episode don't allow us to deduce that much. But in each and every case, the possible sapience of the creature is gone. And the only decision Kirk faces is whether to use the stun or kill setting.
Using more of those salt traps? It's not working. And the fake McCoy's suggestion of dropping the "trap" part shouldn't make any difference. The creature couldn't tell the difference, and certainly wouldn't trust it.
Timo Saloniemi