The word khaki actually comes from a word that means "soil-coloured". It's generally means a yellow-brown colour (so more of a beige).
But khaki has been used for military uniforms around the world, and different places choose different shades for camouflage. In the early 1900s, the British chose a darker, more green hue of khaki, which eventually started to be called "olive drab".
Haha your colorblind friend is going to judge on colors. So this opinions is based on what I've always been told: that khaki is green :-) Sounds logical since soldiers were khaki as it camouflages them in the bushes. With green leaves... I hope that's logical :-)