I think that it is correct, but not written very clearly. The figures are certainly correct.
If you set your camera exposure based on an incident meter reading, then elements of the scene that have 18% reflectance will be exposed so as to result in an 18% grey (or colour of equivalent luminance). Lighter elements will be brighter and darker elements darker.
If you set your camera exposure based on a reflected meter reading, let's say a spot meter reading for this example, then the element of the scene that you metered will be exposed so as to result in an 18% grey.
So if you use incident metering, you get a 'natural' tonal range, but depending upon the latitude of your medium, you may lose highlights, or shadows, or both, and this may be a particular problem if the point of interest of the scene has a reflectance much higher or lower than 18%. Of course you can always take an incident reading and then apply a compensation when setting the camera.
With reflected metering, you can choose where on the range of luminance levels in the scene you want to put the latitude of your medium, by choosing which part(s) of the scene to meter.
Hopefully this is not just some more unclear words.