I also wanted to comment about Bealzebub saying that one can be 'charged accordingly' because breach of contract. That is simply not possible. The Airline/Capt can surely warn the pax he that will be sued for recovery of damages, but not more than than. If the airline has passenger's credit card details, any further charge would be clearly be illegal. Only a court of civil justice can decide on the matter, and a litigation has to be started first. I wonder how many legal departments in an Airline would go for this.
I can agree, however, that the Airline can refuse to unload any baggage to accomodate the pax. Here they can enforce the contract as it is about objects and not persons, claim security/operational issues and just send baggage to the destination.