Again, I think you're defining omnipotence according to your own understanding, and assuming that it is the only one. Your argument is similar to that which generates the "Can an omnipotent God create a rock so large that He can't lift it?" paradox. The very nature of the question presupposes an impossibility, and then impugns God's omnipotence in the face of the logical fallacy.
You appear to be saying that IF God is omnipotent, then He should have been able to create a universe in which humans have free will AND sin did not exist. Mags is (or seems to be) saying that God could have created a universe with no sin, but then humans would have no free will; and that creating a universe with free will NECESSITATES opening up the possibility of sin, because our will wouldn't truly be free if we didn't have the latitude to make choices that are at odds with His.
Right, I understand what mags is saying, but I've pointed out a couple of approaches to illustrating that "no sin" and "free will" can be compatible logically (human logic may or may not be the arbiter of what is and isn't theoretically possible, but it's all we've got), and therefore not really akin to "god making a rock so heavy god cannot lift it." In other words, I don't think I engaged in logical/semantic tricks.
Mags has never really addressed either except to essentially say that it could not be done. You responded to one of those approaches (god choosing, ahead of time, the moral universe arc in which humans all just happen to make the "best" choices) with a response that I still think is strange: "Maybe you misunderstand the scope of god's 'omnipotence.'" (I'm paraphrasing from memory, so let me know if I got your response wrong.)
I find it strange for a couple of reasons:
1. Anything "could" be and I've said a few times that if god is
not omnipotent in the classical sense (truly all-powerful with no limits) then these constraints, like not being able to effect lack of sin and free will at the same time, can fit logically. You don't suggest a new scope to talk about, though, so the net effect seems to be to shut discussion down.
2. You've chastised others for diminishing god, something that you seem to feel must never be done, but suggesting that I essentially overstate the scope of god's omnipotence seems at odds with that.
If you don't think god is actually omnipotent (by the literal definition), then I'm fine with constraints that it has to work with or imperfect universes. Anyone who believes god is literally omnipotent, I believe, is creating a lot of logical inconsistencies. Which may be fine for someone with faith, but isn't for people who don't have faith.
I'm fine with accepting that people of faith have their faith. It doesn't bother me. But there's nothing to discuss in that. I feel that if people of faith want to engage people lacking faith on such matters, they do need to engage such people in the logical realm, because "You just need to have faith" clearly doesn't get us anywhere if we don't have any reason to have faith.