That is incorrect. There are 2 modes, Horizontal Distance mode and Actual Distance mode. Actual distance mode measures the actual distance from the range finder to the object being ranged. Actual Distance is not
"Angle Mode". Horizontal Distance mode is a calculated horizontal distance based on inclination. When in Horizontal Distance mode you will see a angle symbol < on the right side of your screen. Horizontal Distance is the default mode. If you want to measure a distance up or down hill to calculate bullet trajectory you use the Horizontal Distance mode measurement.
Here is a screenshot of the manual showing the settings and defaults.
Here is an image from Nikon's website explaining Horizontal measurement