My guess is that it's like a position I've worked before. You have your IT guy who needs to know all the technical stuff and he, of course, has to have a boss (everyone has to have a supervisor except CEOs and people at very small businesses, that's just life). Now, this boss likely supervises multiple people and the IT guy is only one of them. In these cases, the boss doesn't need to know everything about IT, but he needs to know enough to adequately manage said IT guy.
Alternatively, this could be a situation like one my friend is in. He does web development and everyone else in his office is in sales. He helps out sometimes if they need computer help, but he mostly just does his web development (the main office actually handles most of the IT stuff, they are a satellite office). His boss (again, he has a boss, what a shocker) has to know enough about the tools he uses for web development to accurately judge his performance, have some idea of what is reasonably possible in a reasonable amount of time, and potentially hire my friend's replacement if he leaves. He doesn't have to be an expert, he just has to be familiar (or technically savvy enough to BECOME familiar).