Go into the contact list preferences, edit your contact list layout, and in the contacts section, check the box that says "Show", and you will have a few pulldown menus that let you choose: "(idle) Status", "Status", and "Idle time". That should do it for you.
It is possible he is selecting to display idle time only, where the status font color is matching his background, which would explain the "it just makes the status disappear" comment.
Please make sure this isn't the case, and be sure that the protocol you are using in fact supports idle times.