You don't need Bonjour for iTunes. And Songbird is stuffed full of plugins and other bits. It's feature overload, but it can't even handle the basics even half as well as iTunes.
While you're right, and I won't disagree that it runs pretty bloated, it's better than the 4-5 constantly running processes that iTunes installs without your chosing.
And Tom, that guide doesn't excuse it. They should simply give you the option of running Bonjour or not. Why do you need a guide for deploying iTunes in an enterprise environment?