Okay, but he had the rights to keep em there in order to make an... exchange? What's the pourpose of an exchange if you mustn't keep coins in there? One can't possibily always do flash exchanges, you may have to keep coins there for 1 or 2 days or even 1 week if you want to keep an eye on some markets to do some successfull trades.

As the comparison "stocks.exchange = coinergather" well it made me smile, but I thought about that scenario too. Prices sometimes strangely high that tempts you into selling many coins. But later on when you have to do a BTC withdraw of medium-large amounts, your account gets blocked or disabled for no apparent reason. A guy reported this experience on slack, dunno if then he fixed or what.