So I finally got the specific details from the community manager on the rules I would have broken of the TOS:
1) self-afiliation
2) abusing rewards
They have already banned several users for the second part. So, I won't consider it as a serious claim. But the first part is unique. It can't be considered as a vague claim. Does the user also participate in the tournaments who have referred you to Duelbits. Are both of you KYC verified at Duelbits?