Betcoin.ag is a reputable casino, so I trust their words. There's so many accusers who create fake accusation because they're mad when they're doing a trick in order to win and make money. As your case is arbitrage trading and they not allow you to do that, it's your fault then. However they're already want to return your initial deposit which mean they're not confiscate your funds at all.
It is my first and only account with Betcoin.
You mean if a bookmaker keeps the winnings and only returns the deposit then it is OK. Would be a great business model, probably it is.
Betcoin has absolutely no proof that I placed arbitrage bets. Because there can be no proof. They claim it and the customer has to accept it!
you can't talk about a reputable casino. If the would close the account, even this is hard without any proofs, but retain the winning money? This is not correct.