First of all, why did Satan want Moses body? Answer: Don't know and don't care. That's not the point of the scripture.
The point of the scripture is to help us understand how to deal with the powers of hell that work against us.
All through the Bible, we see situations where Satan tries to mess things up. For example, Daniel in the Old Testament and Jesus in the New Testament.
But how do you fight something that even the archangel Michael wouldn't fight?
When Michael invoked the presence of God into the situation, Satan was defeated. There was no struggle, there was no supernatural wrestling match that ensued. It was over.
Followers of Jesus should seek God's intervening power against Satan and his forces of evil. But how do you do that?
Worship. Worshipping God invites His presence into your life. While Satan may try to stay, in the end, he always loses.
PRAY: Dear Jesus, I need your presence in my life today. AMEN