Perhaps I'm not understanding part of Dr. Bill's original question, but I think this use of exploitation is pretty clear - it means that whoever is collecting this baronnie (presumably the Baron, no?) is somehow unfairly using the labor of employees/tenants/serfs/whaddayagot to obtain great profits - see definition #2, courtesy of AHD:

1. The act of employing to the greatest possible advantage: exploitation of copper deposits. 2. Utilization of another person or group for selfish purposes: exploitation of unwary consumers. 3. An advertising or a publicity program.

Having provided what may in fact be a supererogatory explanation - What is up with definition 3??