it is well know that the book is crap, he don't rly need waste his time
because arthas is the reason of why the forsaken are what they are, and since they calia didn't give a fuck about then, there is no a single reason to care about her, just because they hold Tereneas in some place don't mean it will extent to the person who gave up on then and gave up the right to rule, until she died and gained a quest from a outewordly source