Yeah; whatever the AIs are doing I wouldn't call it "information dense" like the abstract does. I'd prefer the hypothesis that there are complex patterns in speech related to successfully communication information to a limited human brain and the AIs aren't complex enough to model them yet. Or the signal is being obscured somehow.
I'd go with "high entropy", since the text maintains the same elevated level of density all across it, regardless of the level of importance.
They're picking among most likely tokens, which are ones with least entropy and so least information per token.