This is a hard problem I think. Sometimes news that is interesting and popular is also controversial or just click-bait BS, so you have an ethical vs. interesting news dichotomy. Day-old-news will probably not be interesting to people who already read and discussed the topic the day before. Also consider that if only a few people are curating it there will be other discrediting flaws that might not be caught until more readers see it.

Also, keep in mind that if users get sick of the same kind of articles being posted (which could likely happen given biases of the curators) instead of blaming the users for upvoting (like on HN) they will blame the service instead and will likely stop using the service altogether.

Edit: I could see this working with a small group of individuals that are like-minded to the biases/opinions of the curators.