My focus on intelligence is that I know exactly how much of a difference it makes to decision making. That's because I grew up in a gifted family (father 185 and brother 185) and the reasoning process is very, very different in people with that kind of intelligence. Also, most of my close friends are about the 160 range. One of the things that happens is that people think you are wrong because they don't arrive at the same conclusion...
You will also note that I say "we need highly intelligent leaders, and we have to find a way of establishing that." I did not promote a particular IQ test. I used an accepted figure because people generally understand that 140 is genius.
In the days that I headhunted for CEOs of companies, anyone who applied for a CEO position of a major company had to do numerous tests - IQ, personality, character, etc.
One of them turned me down on the basis that I had the highest creativity score they had ever seen, but make no mistake if this is a part of finding CEOs, what's the problem with establishing suitability for political leaders?