I see what you mean, but you're adding stuff to the story to get there. The story doesn't talk about A&E's abilities to trust or not.
Using just what we have in Genesis, the anology makes sense.
It does not require a lot of logical deductions to arrive at this conclusion. Eve's dilemna as presented in her dialogue with the snake is clearly one of who to trust. The snake does not attempt to convince here by logical arguments appealing to here knowledge of things. He instead attacks the credibility of God by interposing his own opinion on what will happen if she eats the fruit.
But they didn't die when they ate the fruit, like god said, and they did get the knowledge like the snake said. They didn't know which one to trust... and that's the point of the analogy.
The fact that they didn't have the knowledge of good and evil does not mean that they didn't have the required knowledge to make the decision to trust God and not the serpent. They knew that God was the creator of all things, that he was the one who established the natural order of things. And in this natural order, he had given them dominion over all living things. They knew the serpent was a living thing, and threfore they had dominion over it, as did God, who had created it.
They had all that was necessary to make the correct decision.
It's like if you're house is on fire, and you are in a room full of smoke, and there is a door in front of you that can potentially lead you outside. The problem is that you see through the cracks that the fire is just on the other side of this door. Your friend with you tells you to open the door and get out of here, but you remember that you were once told by a firefighter that in this situation, you don't open the door because the fire will burst out and most probably burn you. Now, in this situation, even if you don't know the physical reason behind this phenomenon, even though you don't know that this is because fire consumes oxygen, and opening the door would fuel it even more. Even though you don't know any of these things, it does not mean that your decision is a crap shoot 50/50 chance. It does not, because you know the firefighter who is giving you this advice. You know that HE knows the reason this will happen, you know that he was taught and trained for these situations. And so the correct decision, even if you don't understand it, is to trust him instead of your friend who knows shizzles about fires.