Calia never made a claim to the Horde she was bought in due to Voss and the bulk of the forsaken asking her to help, also Voss is the acting leader of the forsaken. We don't know what Calia is quite yet, so calling her a abomination among a population of collective beings who are by nature are abominations in some kind of way is a stretch. Veleera don't give a fuck about HvA she care about individuals.