This is a silly meme. If you look at government data on college degrees (which only goes up to 2004 as far as I can tell), humanities aren't over-represented at all, but account for between 8 and 12 percent of Bachelor degrees awarded[1]. That's History, English, Philosophy, etc. combined[2].
It would be more accurate to say that more people in business should focus on agribusiness instead of finance, or that social science majors should switch to agribusiness[2].
And the percentage of humanity degrees awarded is lower than it was forty years ago, and has been trending down for most of that forty years[3].
Finally, it's rather odd that the author would write that, considering he has both an undergraduate degree and graduate degree in the classics, of all things[4].
[1] http://archive102009.humanitiesindicators.org/content/hrcoIm...
[2] http://archive102009.humanitiesindicators.org/content/hrcoIm...
[3] http://archive102009.humanitiesindicators.org/content/hrcoIm...