It depends on how you look at it. First, I would agree with you that God did not drop a "sin bomb" on Adam and Eve, forcing them to blow it. However, what do you suppose would have happened if they passed the test? Would the serpent have slithered away, defeated, never to return? Or, would he have done what we all know satan does all the time, keep trying? Since we know for a fact that they DID have the potential to sin, unlike Christ, they would have cracked after some amount of time. We know this was by God's design since He could have easily protected them from that potential. But He didn't. So, everything happened exactly as God ordained it. Does that offend their free will to sin? I would say "no".
I for one like the way Harley has described this in the past. I believe, (Harley correct me if I'm wrong), that he has said that Adam and Eve simply didn't have the tools to know what to do here. Eve DOES come off looking like a total ditz and would have been easy pickings for the serpent. God, of course, knew that and allowed it anyway. This is very different from God "inserting" evil into anyone, but it also shows that God's intent was that the Fall happen.
They would have lived happily and multiplied, just as God commanded them I suppose. [though I am not sure where all the people would have lived on this planet if everyone who was ever born was still alive and multiplying! The Bible doesn't address that..."minor" point]
Would the serpent have slithered away, defeated, never to return?
Evil "exists" only as long as there is potential for sin. That, of course, is intrinsic in free will. By giving us freedom God also permitted evil. That freedom is necessary for us to love God by choice, otherwise it's not love.
Since we know for a fact that they DID have the potential to sin, unlike Christ
Christ's human nature was no different than Adam's, so it too had to have a potential to sin.
they would have cracked after some amount of time.
Speculation.
We know this was by God's design since He could have easily protected them from that potential.
Wrong. In order to be free, one must allow that potential.
So, everything happened exactly as God ordained it.
Everything happened as God knew it would, based on their free choice, by His permission.
Adam and Eve simply didn't have the tools to know what to do here.
Of course they did. They could have repented. The act that sealed their fall was their refusal to repent when caught. Adam blamed God for giving him "that woman" and Eve blamed the serpent. All they had to do was repent. God gave them ample opportunity to do so.
This is very different from God "inserting" evil into anyone, but it also shows that God's intent was that the Fall happen.
If God created Eve "ditzy" enough as you say to be easy pray then God set her up. It's no different than leading a child consciously to step into the traffic and then blame the child for getting hit. God gave her freedom to choose and she abused it. That's why we have lawyers.