I think given how fucked up this earth is despite God's commands it's pretty clear that a power differential doesn't get in the way of a disobedient heart. As someone else said there are other moments in the Bible where there was a back and forth between God and a person where their hearts weren't immediately in it.

I think it undermines any religious person's free obedience to God to say that His commands are given under some sort of duress because of a power differential. Yes, religion can be used that way between those in the church who prey on the vulnerable. But a relationship with God is different, especially when grace and forgiveness are part of the equation (yes Jesus hadn't died on the cross at this point, but still).

Mary was already ride or die for God, out of her own free will.