I think it wasn't because of the inactivity of the account, 'cause my account has been inactive for weeks and I am still able to use it now.. Anyway, I would suggest that your friend should create a new one...
Creating a new account is not a solution, I think wherever you are or wherever you are in a forum then plagirism is a very undesirable thing, copyright infringement is an action that ends in a criminal act. This is only a lesson for him or for anyone, appreciate the work of others and I think it is not difficult to include a reference after you quote someone else's writing.