I think that the controller over controlled this one.The pilot of the second aircraft is only saying that if he is sent round,it is now an emergency.So simply land the first,then land the second.No problem.If the second goes around,then that's when you squawk 7700,and everyone knows this is an emergency.
There are many aircraft at all airports,that will be very tight on fuel if sent around.If they all said the same thing,then everyone will be going around,and then squawking 7700.
