the portion of curation rewards that is not given to the curators due to the early voting penalty will be returned to the rewards pool instead of being awarded to the author
This section still sounds to me like all the curation rewards lost to the early voting penalty return to the pool. It says "curators" plural.
That is where the confusion comes in by reading that portion without taking the whole section in context. The paragraph above, and the heading makes it clear that they are only talking about the author's self-vote portion of the curation reward, so the author doesn't get the full value of his own upvote, as well as additional curation rewards, which should be given to the curators.
There are as many curators as there are votes on a post. They are the ones who should receive the curation rewards, except for the lost curation rewards from voting early. Those go to the author, except for the author's self vote portion, which returns to the rewards pool.
It is certainly confusing. At no point does it say anything about about any of it being returned to the author. Mind you, at one point rumours were going around that practically the whole vote before 15 minutes would go back to the reward pool. I'm certainly glad that isn't the case! nervous laugh