Stated more clearly: "Once you get to a comfortable multi-six-figure salary, you'll find you don't get spectacular percentage increases quite as often." That seems applicable to any field anywhere.

The article correctly states that an older guy is likely to be making three times as much as a new grad, while incorrectly assuming that he's still only capable of using the technology he learned 20 years hence.

So, no. The fact that the author couldn't actually come up with any statistics implying that being old is actually a bad thing, despite combing the Bureau of Labor Statistics and Census for data, seems to be a good indicator that there's nothing to worry about.