You are dodging. You are still not telling us why God cannot lie. You want to introduce other things into the discussion like time, etc. Indeed, by saying He is not "bound by the constraints of His own conceptions," you seem to think God could lie.
I also wonder why you introduced the "future" if it applies to past, present and future. You wrote, "No, what it means is that whatever He says comes to pass." Why complicate matters if you really think it applies to past, present and future?
It is an important question. Eve would not have been deceived by the serpent if she had "grasped" that it was impossible for God to lie. She allowed her mind to entertain alternatives, "Well, maybe God was deceiving us when He said we would die if we ate of that tree." How could she have faith in God if she thought maybe He had lied?
I say God's purpose in creating man was Love. God wanted people He could love. It would be wonderful too if they loved Him back; and since genuine love is a matter of choice and cannot be programmed or compelled, man was given that choice. If God lied to people, He'd be undermining His own purpose in creating man. Why would He do that? If He wanted what was best for them, He wanted them to trust him and to believe in Him. God is Love. It is what He is. For God to lie would be betraying Himself. It is God's Love that "constrains" Him from lying.
Eve began her way down by doubting God's goodness and truth. That suspicion led to other things. For me, it seems simple: God is Love -- there is no reason to doubt what He says since He loves us and wants us to love Him.