To demonstrate what a barrier LaTeX is, he illustrates by writing the title of a paper, the author, date, and first line. The result is obviously human-readable in a word processer without special training, but not in LaTeX.
And that shows, at best, that if all you do is write papers with the author, date, and only thefirst line, then perhaps Word is better suited for that particular task.
But then, writing real documents is far more demanding than that.
For instance, let's say you're trying to publish your paper in a document, and your paper has more text than a single first paragraph. You find out that the style guide imposed by a journal demands that all your figures are placed at the end, in annex. In LaTeX, all you need to do is add a single line of text (include a package). How much work does Word forces you to do?
And I won't even get started on the fact that MS Word fails to support any vector graphics format.
1) The person has no knowledge of LaTeX 2) They've never seen a markup language before 3) Yet somehow they've received this file, devoid of context, instead of the PDF, and they've opened it up in a text editor. And somehow this is relevant to something they're doing.
Who is this person? What are they doing? How is their experience worse than the guy with no experience of Word, no knowledge of Word who opens up the equivalent Word document in vi?