Where does it say how experienced this pilot was in that article? Isn't it ageism to assume/imply that he is more experienced just because he is older?
You're correct that it doesn't say how much experience the pilot had. (But it does take quite a bit to get a rating for that type of airplane.) But neither does it say anything about the pilot's abilities. There are people who are perfectly competent to fly airplanes, or drive, at that age (or much older), just as there are others who wouldn't be competent at 18. (Why does auto insurance cost more for younger drivers, I wonder, if age makes you incompetent?)
The point is that the poster was simply looking at a number, and drawing conclusions about the person that might not be valid. Just as, in a different context, he might look at skin color and draw similar conclusions.