Just because they had 800 glyphs, it does not mean that they only had 800 words. There were probably complex ways of combining them to mean other things. Just for example, something like “Eight Rabbit” did not have to be part of a shopping list for dinner, but rather the name of a specific ruler. Perhaps someone can give additional information on this subject.
Perhaps I was a bit too simplified (eg elegant) in my statement. But isn’t it a hard stretch to combine 800 hieroglyphs to make it an elegantly useful language.
I don’t deny their inventiveness; I do question the professors characterization.