I THINK if you change the email, and try to change it again, a confirmation email gets sent to the email...
I had the same problem, but thought that if you needed the email to get the password, and if you try and change the email on acct management, it would send a confirmation email...
say no and he cant do shiet
basicaly, SQ/A
and email, are really the only things needed to keep an account...
unless he calls blizzard... :S
anyway, change all info thats changeable, doesnt have to change the name, but address/email/phone and what not