Any Pilot must be prepared to go around until they have a landing clearance! To ignore a go around call and to then land without a landing clearance I am not surprised that the Captain has been asked to explain himself.
a go around call cancels a landing clearance even if one has been given
To land a heavy jet thinking you can stop with another aircraft already on the runway is on a wing and a prayer and not based on any computed data.
How does the pilot judge the runway available? Going around the pilot could always break right or left if there is another aircraft airborne