Here is the thing. This is not a country or city that has police and courts. It is an online game provided by PlayWith Interactive. People are allowed to play here as long as they agree to the Terms of Service - which is accepted by continuing to create an account. In those terms of service you agreed to there is nowhere stating that they must prove or even explain anything to people that they block from playing. This game could disappear from the Internet without any notice or explanation - with no legal requirement to provide one. Your account and/or IP can be blocked at any time - and they would not even have to tell you why. They most certainly do not and will never prove anything to you or me if we are banned. In fact in the almost 9 years I have been around here they have never provided proof for a ban or blockage. This is just he fact of life anyone must accept if they want to play here. They don't care how much you have spent on your account. If they want to shut it down, they will and no proof is needed (though to do so on a 'big spender' I am sure the GMs must provide a good reason for doing it to their management).
Call it unprofessional if you like, but this is their universe. They are the Alpha and the Omega here. We are the peasants that pay the taxes - they are the lords that collect those taxes.
If legit I am sorry your friend got banned for what he says is a misunderstanding. But that is how the online gaming world rolls.