I don't understand the article, particularly because airline travel is the cheapest it has ever been in the history of aviation.

Is the author asserting that mutual funds are preventing air travel from being even cheaper than it already is, which is the cheapest it has ever been in the history of aviation?

This is, of course, excepting approximately six months post-9/11 and the winter holiday season post-financial crisis when the industry was on the verge of collapse and nearly every carrier operated at a loss temporarily both times just to keep people in seats. Except for that brief period in time airline travel is the cheapest it has ever been in the history of aviation.