The AutoHidePanel doesn't check if the user is an admin or not to determine if they can see the content. It only checks if there is content within it's panel, and if not, it doesn't display at all.
I answered a question about hiding links for non-admin users the other day. You can find it here: http://www.mojoportal.com/Forums/Thread.aspx?thread=5045&mid=34&pageid=5&ItemID=9#post21037.
Please keep in mind that the solution I came up with only hides the links, it doesn't prevent users from manually typing the SiteMap url into their browser and viewing the SiteMap that way. If you want to prevent users from seeing the SiteMap altogether, you will have customize the SiteMap page.
May I ask why you want to hide the SiteMap from users?