It's an intriguing notion, that employment in a field should be limited to people within the range of the average ability within that field. It does make me wonder if this police department would hire, as a detective, a police officer of higher intelligence who had gained his or her beat experience in another city, or if their detectives are also limited to average intelligence.
At one time in Taiwan, your college entrance exam results determined not only which college you could attend (and everybody in Taiwan seemed to know and agree upon the rankings) but what your major would be. As it was explained to me, people who landed in a particular range of scores would study architecture, for example, whether or not they showed any particular aptitude for that kind of work.
Whether or not there is an official policy, I am certain that there are HG and PG folks who cannot rise through the levels of their organization because of a tacit and unconscious version of this policy. Management is usually chosen from people with cognitive abilities close enough to most of their employees that they are perceived to have "soft skills" or "interpersonal ability". And there is probably an even larger group of PG and HG folks that would not touch a management position with a 3 meter pole because they find trying to relate to people of average intelligence* all day, every day to be exhausting.
*on a level that is perceived to be meaningful
