In my experience people that are very verbose, that talk or write at great length and with ease, tend to have a dislike for terse formulations. Sometimes to the point of being offended by it. Math is just about the ultimate in terse notation and perhaps the author is one of these verbose people.

The same thing can be seen with programmers: The verbose programmer writes a lot of lines of code and is proud of it, while the terse programmer is proud to remove or simplify code.