So God didn't have the power to absolve her as has been described in Catholic canons? Wow, omnipotence is so limiting...
That statement shows a gross misunderstanding of sin and redemption. God cannot look on sin. It cannot be absolved. It can be forgiven with the shedding of blood.
Romans 6:23 For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.
Hebrews 9:22 Indeed, under the law almost everything is purified with blood, and without the shedding of blood there is no forgiveness of sins.
If God could have simply absolved Mary's sin, He could do it for everyone. Then there would have been no need for Jesus to die.