You are right, but you know this is a centralized exchange. I can't see any valid reason to disagree with them except to centralize regulation. We must say that they took the right and real-time decision to save their customers. They didn't prevent you to spend your money, but they prevent you from scammers which you aren't aware of really. If you were really happy to scammed or owe money, then it wasn't difficult to withdraw another address then send it to the scammer. They have notified to their users why they prevent sending funds to the scammers. I had seen warning noticed when open coinbase wallet.