I looked through the ToS (Terms of Service) although i couldn't find anything about rigging games being against the rules it was probably terminated because it was an alt. If not then this (which is apart of the ToS) dictates they can terminate an account without or with very little reason.
7. Termination
A. Warlight's Right to Termination
Warlight reserves the right to terminate Your Account, limit or prohibit your participation in any game or game for without any reason. Immediate termination will result for obvious reasons, including, but not limited to, any violation of these Terms and Conditions, improper conduct or abuse by You as set forth in section 13. By registering for an Account, You consent to allow Warlight to access Your Account information to, among other things, investigate complaints or other allegations of abuse. Please note that in certain circumstances where Your Account is closed by Warlight for a violation of these Terms and Conditions, Your winnings may be voided and not returned to You. In such an event, Warlight may use these winnings to defray the costs of administration and enforcement of these Terms and Conditions.
Edited 10/7/2015 07:51:11