I'm not very convinced here.
Unlike the Chaldeans, ancient Egyptians don't seem to have had any interest in depicting comets. They're certainly not in other astronomical reliefs (at least, that we can tell.) They weren't particularly good astronomers, and they don't seem to have any records of Halley's Comet, which would have been big and very spectacular -- or any other comet.
If they suddenly decided to commemorate a comet, it would have been so unusual that they would have written about it. The texts next to the image would have talked about an omen or an unusual "sign" in the heavens.
Your remark about the "flower snake" is confusing to me... there's no such concept for the ancient Egyptians.
(that's all I have time for at the moment. Others will be here no doubt to comment as well.)
-- Byrd
Moderator, Hall of Ma'at