Actually he can use an incident light meter.
I find it funny that people who do not know how to use them, think they will not work. If he wants to photograph the clouds all he has to do is hold the meter between the camera and the clouds with it pointed at the camera. If he wants to meter the light behind the clouds all he has to to is replace the dome with the disk and point it at the part of the sky he wants to photograph. Of course it helps to have some experience that well tell him when and how much to compensate for special conditions.
I have been preaching incident metering for decades now, and it amazes me how many folks have come to see it my way.