If not already done, the CAA legal dept need to explore the concept of Joint Liability so that when the likes of football agents etc need to hire an aircraft, they know full well that an AOC operator is the only option.
Perhaps when the MPs get involved, the Department of Transport can give ‘direction’ to the CAA to draw up proposals for new legislation.
PPRuNers might consider writing to their MPs, and Grant Shapps, Secretary of State for Transport with your concerns.