This is an example of the Captain's authority - having the power to stop a flight. Once the flight has started, the time for sorting personal issues has passed. But after the plane has returned to the stand, the question that now arises is who do you offload? One, both or all? As to what happens to the crew members who were arguing is up to the company but the most important thing was that the whole debacle was brought to a halt as quickly as possible.
PM