Since leakage to earth is not really covered in in service testing and he is using a PAT tester I would assume he is measuring the protective conductor current or touch current in accordance with the COP. which is the current that does leak to earthed parts.
In answer to the original question, there is not really any "get out clause". I would just say make sure you are testing correctly and see if you get different values, it is a bit of a pass fail situation for in service testing. But 3.5mA does seem a bit high for a smart board projector, they may be just a cheap power supply.