That seems valid at first, but if look at that premise closely, you'll see that even assuming wordless thoughts always come first, doesn't mean that during the process of thinking they don't give way to words. That is to say, thoughts can be a precursor, but words do offer a framework which you can use structure thought.
That's specially handy for abstract concepts, like individuality, the split of the self and the world, which are fundamental to thought as we understand it through language.
Nothing prevents you from understanding a concept with the help of language and then using the concept by itself, detached from the symbols you used to arrive at it, to think. But that requires a certain effort and intention that maybe is what the article is aiming for.
is something many buddhists and hindus would consider an illusion and fundamental error