Paint colors

[hd36knuckl]

I fail to understand the logic that allows a bike to be custom painted, as long as the custom color was used within 5 years of production. Where does this illogical logic come from? How can a 1945 machine be painted a 1950 color and be considered original or restored? How could a machine built in any year know what color would be available up to 5 years later?
In the very early days Harley-Davidson offered to paint a bike any previous years color. However this offer dissapeared from sales literature by the mid thirties.