Here's the link:
The US military basically requires that a recruit have graduated from highschool as a mimimum. There is a strict limit placed on the number of high school dropouts that will be accepted, which limit is far less than the number of dropouts with a GED who want to enlist, let alone those who don't have a GED.
The reason is that drop-outs, including drop-outs with GED diplomas, are less likely to complete basic training than those who have completed high school.
That necessarily implies that accepted recruits have at least average intelligence as a minimum and that means that the average intelligence of a recruit who has passed basic training is above the average of the general population.
So I think that the author is mistaken in this assertion.
But overall there is a valid point to be made. Learned legal scholars, politicians, journalists, academics, intellectuals all, at least in their own minds, will spend hours to second-guess a decision that an ordinary soldier had about a second to make.
And let us not forget that the downside risk of their learned deliberations does not include the potential death of themselves or any of their learned colleagues.
That is, I think, the point that the author was, perhaps badly, attempting to make.