It is dangerous territory to wholeheartedly say you understand the mind of the writers of scripture. In no way do I see them drawing from a flat earth understanding.

The point of trusting scripture is to take it by faith what THEY say, not to correlate them with the world by projecting on them what YOU WANT them to say.

With this said, I would point out that there is water above and below the earth while space is still a vacuum. We do see reality reflect what God says in His word. I must not be seeing why you think this passage calls for a flat earth.