#3 - Sept. 25, 2010, 3:39 a.m.
I don't think your friend was banned, Release - he likely received a message similar to 'This account has been locked for suspicious activities.'
He should check his registered e-mail address for more information regarding this lock on his account. As others have mentioned, the use of most proxies or tunneling services are not strictly prohibited, but they are not supported either. As a result, situations like this can arise if we see suspicious activity on an account.