Any Pilot must be prepared to go around until they have a landing clearance!
Not if going around is more dangerous than forcing a landing.
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
Ignoring and disregarding are not always the same things. Controllers and pilots are humans. Our task is to bring the aircraft down in the most safe manner and not to follow orders to the detail. I know that there is a big cultural difference depending on our background but staying alive is a combination of following rules and procedures, but also to be able to think outside the box sensibly when the rules introduce new hazards.
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.
I'll think about that next time I use my landing distance tables/software.
How does the pilot judge the runway available? Going around the pilot could always break right or left if there is another aircraft airborne
Easy, it's called airmanship, if you fly to an airfield with few runways, regularely, you will soon know the distance for each turn off by heart. If the aircraft is beyond an intersection 2000m down the runway, you know for sure that you will safely stop before the other aircraft, or steer off the runway at a low speed. Thats' in my opinion a much safer option than a midair collision.
If you know your aircraft, you do not even need your landing distance table to estimate your landing roll to within 200m accuracy. That's why we do autobrake max demonstrations during training to show how efficiently and smoothly the aircraft stops within the first 1100m of the runway. I have even used it in an emergency situation requiring a threshold speed of more than 195kts and it works just fine.
No you cannot break left or right. You are limited in bank angle and performance. Making a go around requires the PF to focus on his instruments and the handling of the plane while PM has to monitor him and retract flaps, gears, set speeds and remind PF of missing items in order to gain performance needed. If four eyes are kept looking outside for another unknown aircraft, performance may be even further limited since configuring and handling of the aircraft may be compromised. Forcing a performance limited aircraft will introduce much bigger hazards, aspecially when you are close to the ground.