because he can
Sometimes "because" is the best reason to do something. Even if the use case and goal is gain more skill in a given area.
You might also find your single sign on and AD support with Novell's Suse distribution. Mind you, single sign-on is not always desirable. The pentester pops a user password and then own your network to the extent of that user's permissions; soon after, the rest of the users and escalated permissions.