I did field work in Panama and Ecuador at the same time/place as one of the authors of this paper (Roland Kays; he's also the first person to cross the isthmus of Panama on a unicycle). The field work required to find and observe olingos and olinguitos is pretty hairy. They are nocturnal and arboreal. You can radio track them, but first you have to find them and catch them. Not an easy thing to do in the understory at night.
Maybe I'm just not reading the article carefully. Or maybe these scientists are in line for a Nobel Prize for finding a "carnivore" species that "feeds on fruit". Or maybe it's just a very poorly written article.
The are talking about taxonomy (order Carnivora in the class Mammalia) not diet. Many tropical carnivores (kinkajous, olingos, tayras, coatimundis, ...) eat large amounts of fruit. They will also eat "crunchies" (invertebrates, small vertebrates) when they come across them.
My armchair assessment was that its long, finger-like paws were for digging those "crunchies" out of trees, etc. but was disappointed when the article didn't mention anything about it.
I never knew until now that there is no taxonomical classification for Omnivores.