Chances are, the fool arrived at 4.5kW from the amount of power required to accelerate the flywheel, charge the capacitors, or power whatever energy-storage device he's got hidden in the dishwasher. Otherwise, requiring a constant 4.5kW input to get 300W output is a pretty inefficient and poor first step on the road to free energy. Most modern internal combustion engines are more efficient than 6.7%.
I doubt he is the fool. He has us writing about him, not the other way around.