Exchange 2003 – Hide GAL from User

I don’t know if this is even possible but… I have a very annoyed user (top management) that does not want to see the GAL in his Outlook. I know how to make it to where it doesn’t automatically display, but it is still there in the drop down list. He wants it gone. Please verify for me if this is even possible, as I have been pondering and researching this for a while now. Thanks in advance for any help and any suggestions are very much appreciated as well.