All he could possibly do was pretend. And pretense is the enemy of integrity. Integrity is all about truth. Our own sacred identity is dependent upon integrity and is therefore at risk so long as we pretend we're something we're not, so long as we routinely pretend one choice is about as good as any other choice. Experience alone informs us that some choices are better than others.
Some choices dignify life and ennoble our humanity, while others debase life and our humanity.
Some things are true, others are false. In our tradition Satan is known as the Father of Lies. He is the great pretender. He personifies our human capacity for self-deception of every sort. That's why he figures so prominently in the story of the Garden of Eden.