Just to add to what Spoonbill has said.
Aerodrome and Approach/Approach Radar services outside controlled airspace are classed as Air Traffic Advisory services. An Advisory service is provided for the same purpose as an Air Traffic Control Service to participating aircraft outside controlled airspace. The service is delivered in the same way as a full air traffic control service and pilots are expected to comply, unless they state otherwise.
Several points come out of this. If you are flying IFR and you call an approach unit without radar you will get more than just a FIS. A procedural approach unit will provide you with standard separation against other participating traffic. In fact the Manual of Air Traffic Services Pt1 states that "Standard Separation shall be applied between IFR traffic receiving a servicefrom an Approach Control Unit outside controlled airspace". Note it does not even specify the type of service being provided.
The instruction to orbit outside the ATZ is similar. You are operating under an advisory aerodrome control service. You do not have to orbit if you do not want to, but do not forget, you need a clearance to enter an ATZ even in Class G airspace. It is easier to issue that clearance if you are complying with instructions issued, rather than just doing your own thing.
No matter where a controller is operating it is part of their brief to maintain and expedite an orderly flow of air traffic. Air Traffic Control units outside controlled airspace are there to assist with safety, but without the full restrictions you would get with controlled airspace.