I am going to throw my 2cents in. I would agree that Adams nature was corruptible. I would also agree that man became a sinner by nature at Adams fall. Mankind became children of wrath by nature (Eph 2:3) and spiritually dead (Eph 2:1) at the fall.
On the other hand, in the sovereignty of God, Adam was going to fall. God had a purpose for Adams fall, and that was for his glory. The issue of all creation is the glory of God. God's glory is manifest by mankind and the angelic realm seeing all the attributes of God. So then, the love of God must be manifest, and the justice of God must be manifest. I guess the justice of God could be manifest because of the rebellion of Satan and many angels, but God chose also to manifest his justice in the judgment of sinners in the realm of mankind. For God to manifest his wrath against sin, sin has to exist. So then, in the sovereignty of God, Adam had to fall so that God can manifest his wrath, judgment, and justice. God also manifest his love in redeeming a people for himself.
I would not agree that God created Adam with a sinful nature, but I would also agree Adam was not created with a holy nature, or a righteous nature. Of course no one here is saying that. The term innocence is the common term to discribe Adams nature, and I think that term works. Adam was not holy or righteous, he was not by nature a sinner, but he was unconfirmed in either righteousness or evil. He did not have a knowledge of good or evil when created. His nature was changed when he received this knowledge of good and evil from a perspective of rebellion against God. From that moment, spiritual death occurred. This takes us back to the statements of Ephesians 2 and Romans 5. In Adam all died. Mankind died spiritually not at creation, but at Adams sin. It was at the tree of the knowledge of good and evil that we all became rebels against God.
So then, to answer the question in the OP, if Adam had not sinned, then God would not receive the glory of manifesting his love toward rebels, and manifesting his wrath and justice toward sinners.
I am saying that while Adam was not created with a sin nature, in the providence and sovereignty of God, God intended for the fall to happen all along. The fall was not some accident where God said "oops, I did not mean for that to happen, now for plan B."
---Now for a little fun--- Satan had been cast out of heaven during his rebellion. Can someone remind me where God cast Satan? Was it to the pit, or was it the planet kolub? How did that nasty little serpent get in the garden anyway?
If Adam was created morally neutral or innocent, was it God that tipped the scales toward rebellion? As God did this, he did not in any way participate in Adams temptation or rebellion. But neither was God caught off guard. He knew what would happen, and he wanted it to happen so that he could manifest his glory by judging rebels and sinners, and also to manifest his love in saving other rebels and sinners.