Pulling of another rabbit’s hair is plain bullying. This is displayed in the wild where they conform to a complicated social hierarchy. It sounds like she is a very boisterous, active rabbit and nothing can be done about that. Your vet seems to have covered all of the possible medical explanations for the fur-pulling and you were right to check if she was nest-building.

Thus, this is a behavioral problem. After an office dispute, it seems quite likely that the rabbit might not bully the guinea-pig. Rabbits have a tendency to dominate cavies but the previous bullying may be rabbit-rabbit social behavior. You must make sure that the cavy has enough space to get away from the rabbit when it seeks quiet and, as in all cases, that it has a quiet nest box to retire to. Good luck.