Was this not actually an issue about fuel,
I don't think so. If I had to bet I would say it was an issue about stress levels reaching a stage where cognitive processing ability decreased markedly. The straw that breaks the camels back is just a straw. How else can we explain the pilot performing and passing many go around manoeuvres under examination yet in this instant....forgetting to press the correct button.
The real question is why did this guy not perform the way he has demonstrated that he can perform? Stress? Fatigue? Brain aneurism ?