Right the gpu was probably idle. It was a cpu load to test full system running, aka every part needed for a functioning pc since a cpu can't run by itself, and was tested just loading the cpu. It was also tested using a power meter at the plug for just the tower, not the monitor and tower. Hardware meters are more accurate than software which attempts to read from motherboard sensors.
Another way they test in some power consumption benchmarks is to use an amp meter clamped over the wires leading the cpu power plug from the psu. Software reporting tools are mediocre most of the time and don't necessarily test everything properly or take everything into account.
When comparing to an intel system, the same/similar hardware is used...