1. Omarosa really is that rude and incompetent, and is behaving this way of her own volition;
2. The producers persuaded Omarosa to behave in such a way, in order to make for better television, but this will not be acknowledged on-camera. (It's not like such manipulation would be unusual for Mark Burnett. See Deposition of Dirk Been in SEG, Inc. v. Stillman at 32:22-35:22, 37:14-44:25 and beyond); or,
3. The producers persuaded Omarosa to behave in such a way, in order to make for better television, and they also persuaded someone on Bill's team to do the same, with the intention of forcing each finalist to make a decision as to whether to fire the poor-performing employee -- and this will be revealed as a deliberate twist at the conclusion of the final episode.
I mean, she can't just be that bad, can she?