* Sitting in on meetings of things that might be, and calling me in when he feels my input would be useful
* Being a first point of contact for the "customer" when they want to find something out but don't want to poke dev directly (they do poke me directly on occasion when they know it's appropriate)
* Being a first point of contact when I need some information (Who should I talk to to get more information about X? Can you schedule a meeting with the folks from Y so that we can discuss the technical details of something? etc)
He's there because he knows enough about my work and the work of everyone else we interact with that he can handle the management of non-technical details. I, for one, am very thankful that he is there.
Honestly, it runs similar to the argument for an Administrative Assistant. Sure, I could schedule my own trips, and order my own <stuff>, and such. But having someone there that does such things on a regular basis is a huge benefit. The AA(s) at every company I've worked for have always been someone I am very thankful to have, even if we could get by without them. It's all about efficiency.