You can pump and dump a coin on an exchange, without moving money in or out.
You also do not need to convert HIVE to HBD using the blockchain feature - you can just use the internal market. There still was enough margin.
Maybe the coin gets pumped at the exchange and then it hikes up the internal market to that price. The 3 exchanges are so bottlenecked, that the demand can not be filled and someone makes a predictable profit at the internal market and can later buy back their HBD(?)