Why Agnostic?

[Purple Rabbit]

Erm...

I don't think the existence of god is unprovable, only unproven.

This is a complete contradiction with what you just said

Holds God’s non-existence as provable - NO, only highly improbable and (depending on the specific god concept evaluated) in most cases a highly immoral concept

You're right. I have mixed things up. What I meant is this:
1) God’s existence is unproven, highly improbable and (depending on the specific god concept evaluated) in most cases a highly immoral concept. God's existence is not necessarily unprovable but it is unproven so far. It is possible that we still can find proof.
2) God's non-existence is unproven, but not necessarily unprovable. It is still possible that we find a proof of god's non-existence.

Either you don't think the existence of god is unprovable (and thereby think it is provable...double negative remember), or you think the existence of god is unprovable.

You are too hasty with the double negative rule because that assumes a clean divide between unprovable and provable. It may be undecided (or even undecidable) whether a statement A is provable or unprovable. Meanwhile I can think it to be either provable or unprovable, but that is what I think, it is not absolute certain knowledge.