The average PC draws around 50-200W idle.
And as you said, this is more or less what the author found, except that he apparently has no idea how to convert kW/h per hour into watts.
Yes, he's a fucking moron.
Sorry, but you are wrong her. First, it's KWh (KiloWatthour), not KW/h.
The Watt is a unit that is used for measuring the amount of energy used per unit of time, in short 1 Watt = 1 Joule per second.
When electric energy is stored, like in a battery, or measured, the total energy stored or used is derived by multiplying Watts by time, thus Watt * seconds. Since this is not an easy workable unit, KiloWatts are multiplied by hours, and there we have the KWh.
So, if a battery has a capacity of 100 KWh, it is able of delivering 1000W for 100 hours, 500W for 200 hours, 100W for 1000 hours and 1W for 100,000 hours.
So, to make a long story short, the lost capacity of a battery HAS to be expressed in KWh, and the resulting loss of range totally depends on the driving conditions. It might be (numbers pulled from lower opening of intestine) 100 km when driving a constant 20 km/h, or 5 km when driving a constant 150 km/h, since the amount of power drawn on these speeds vary. But I hope you get the picture.
The qualification as a copulating, low-IQ person is totally yours.