Never knew Google had such thing: google_ad_width = 980; google_ad_height = 15; google_ad_format = "728x15_0ads_al"; I assume the user manually changed the ad width!!! It's on this site - http://kalynskitchen.blogspot.com/
Nothing... they wont ban him for that. he will get an email from google asking him to remove the over-rid if he hasnt asked them before hand...
I guess it is not a premium AdSense user, since they have special privileges so I guess also custom banners on request
I just used Firebug in my browser to manually change the width back to 728 and it just left a gap either side of the google ad which could have been filled with a suitable background colour. Risking his account isn't worth it for the sake of design.