I think you responded to my point, but not in a way that is convincing to me at least. If God was willing to destroy the world in a flood before the covenant, and is no longer willing afterwards, then I would say that God has clearly changed. I accept that you could posit that God was always in the same state, one where he was willing to destroy the world before the flood, and not willing after.
But this can be done for any system just as well: instead of saying that the egg was broken to make an omlette, you could say that the egg has always been in the same state: the state where it is whole before the omlette, and broken afterwards. The egg itself is a timeless concept, but we just experience it differently as time passes for us. I don't see why this argument works for God and not for my egg.
I think I would summarize it somewhat differently, that God is (as a constant state of being) willing to destroy the world with a flood whenever it is as it was in Noah's time (which criteria determine this are not necessarily known to us, except insofar as they were met then and are not met now).
So from our/Noah's perspective, that situation has come and gone, has changed, because we're bound by physics and the passage of time and cannot exist in that circumstance any longer. But from God's perspective, that world is always destroyed by flood. It may be the case that the criteria that categorize a world as "destroyable by flood" never exist in our experience of time again, and it may equally be the case that God knows this will be the case.
But God's willingness to destroy the world by flood under those criteria has not and will never change, because God's will does not change.
But this can be done for any system just as well: instead of saying that the egg was broken to make an omlette, you could say that the egg has always been in the same state: the state where it is whole before the omlette, and broken afterwards. The egg itself is a timeless concept, but we just experience it differently as time passes for us. I don't see why this argument works for God and not for my egg.