I think he's ascribing far too great a relationship between colour differentiation and language.
Disagree. I think he got it about right. In fact, I'm surprised the differences are so subtle, except in the case of young children who are in the process of learning the names of colors.
It seems entirely plausible to me, if a person doesn't have a word for the object that is seen, or the sensation that is felt or perceived, there will be at least a slight delay in differentiation.
I believe that certain primitive cultures, remote tribes with their own unique language, do not distinguish between different species of trees. They have just one word to describe all trees. However, that does not mean that such people are not able to visually distinguish between the different shapes and sizes of leaves, and the different textures of bark on different species of tree, but it must surely make the entire process slower and more confusing.
What I find particularly interesting is this lack of specific, primary words that distinguish between blue and green in may cultures, including China, Japan and anctient Greece, as well as less prominent cultures.
This must surely seem particularly odd to most of the readers of this forum who have a fair experience in photography and understand that Red, Green and Blue are the three primary colors. Blue and Green are primary colors yet
certain cultures do not verbally
distinguish between them. That is a surprise, surely.
Attempting to understand how this can be, I recall that during certain conversations in the past, with people who were not into
painting or photography, being surprised that sometimes someone who was undoubtedly intelligent was not familier with the word cyan. Didn't know what color it specifically referred to, although they would certainly have heard of the word.
What's going on here, I ask myself? I'll venture an explanation.
In some cultures, Cyan is the primary color which encompasses both blue and green. That which we consider a pure blue is merely a bluish shade of cyan. That which we consider a pure green is merely a greener shade of cyan. One can get by with just one word for blue and green.