That arrogant baboon neglects to take into account reflection off the firmament. That picture is perfectly consistent with there being a firmament around the edges and reflecting light around the circle.
OK, so you're proposing that light "reflects" along the firmament.
Do you have any evidence for this?
And are you acknowledging that the antarctic has 24 hr daylight for part of the year?
Even if light reflects along the firmament, how does light get all the way around to the other side of the disk, but nothing gets to the arctic circle?
If you can't explain this, how do you know it's "perfectly consistent"?
The system you're "explaining" is ad hoc. Each part is an attempt to explain one observation, with no apparent unifying principles.
Could you make any predictions? Could you tell, based on the "model", when sunrise or sunset will be in any particular place?