This is what my intuitiom tells me to say: You know yourself best!

Apart from that, there's a nuance in the post I can't quite put my finger on at the moment. That's all from me (for now).

You are assuming that there are such things as propositions apart from human consciousness.
The question that you should first make is whether propositions are emergent or fundamental.

There's an observation (which I believe Aristotle made) that if all propositions are AT THIS MOMENT either true or false, then we lack free will

The reasoning is not hard to follow. If "I will have snails and beer for breakfast tomorrow" is true at this very moment, then I WILL have snails and beer for breakfast tomorrow even if the sight of a snail makes me sick and I'm a life-long teetotaler.

You are assuming that there are such things as propositions apart from human consciousness. — TheMadMan

I'd say the proposition "two plus two = four" exists apart from human consciousness.

Well, in a sense, but I think there must have been propositions that God could not have created: for instance, that A = A for any A. God would have to be God, after all, in order to actualize propositions; yet He couldn't have actualized that one (logical self-identity) without putting the cart before the horse.

I think it's slightly awkward to put it in terms of propositions though and could instead be commented on as properties.

God can't both exist a se and have absolute sovereignty at the same time because God has a set of properties (such as being omnipotent, being a person, etc.) but couldn't have had anything to do with why God has those properties (He couldn't have chosen them) as it would put the cart before the horse. In order for God to decide on what properties to instantiate, God must already have properties such as the power to instantiate them and the knowledge of how to do that: so He couldn't have "created" those properties, they had to have already been there, and they had to have been there in a way that was outside of His control.

This is an interesting and thought-provoking question you've posed about God's knowledge of propositions and whether this makes Him a contingent being. I'd like to offer a counterargument that addresses some of the assumptions you've made.

So, assuming that I understand your argument/question, I'm going to put it into premises so it's clearer.

1. God knows all propositions.
2. God creates everything that is not Himself, including propositions.
3. Before creating, there were no propositions to be the objects of God's knowledge.
4. Therefore, God only has the essential property of knowing propositions because He created them. If He didn't create them, He wouldn't have this essential property.
5. As a result, God depends on creation to have one of His essential properties.

First, I'd like to challenge the assumption that God creates propositions. It's possible that propositions, as abstract entities or necessary truths, exist independently of God. In this view, God's knowledge of propositions does not depend on His creating them. Instead, He knows them due to their independent existence as necessary truths.

Second, I'd like to emphasize God's timeless nature. The idea of God existing "before" creating propositions is a misunderstanding since "before" implies a temporal relationship. If we consider God to be atemporal, existing outside of time, then His knowledge is not bound by time either. This means that there is no "before" in which He did not have knowledge of propositions.

Taking these points into account, we can construct the following counterargument:

1. God knows all propositions.
2. God exists outside of time (atemporal) and has knowledge that is not bound by time.
3. The idea of God existing "before" creating propositions is a misunderstanding since "before" implies a temporal relationship.
4. Propositions are abstract entities or necessary truths that exist independently of God.
5. God's knowledge of propositions does not depend on His creating them; instead, He knows them because of His atemporal existence and because they independently exist as necessary truths.
6. Therefore, God does not depend on creation to have the essential property of knowing propositions.

By challenging the assumptions that God creates propositions and that there is a "before" in which He did not have knowledge of them, we arrive at the conclusion that God does not depend on creation to have the essential property of knowing propositions.