I find this a rather faulty logic. I would rather assume most of the DUI drivers in the world did not run into accidents with the intention of wanting to die. That's why its called an accident. Similarly, yes, it seems reasonable to assume to cockpit crew does not want to die, but a plane's flight safety is way beyond the will to live of the cockpit crew that flies it. Maintenance issues, unknown mechincal failure, terrorist attacks, sudden changes in weather patterns, incorrect information given, etc.

A pax places a significant contractual trust in the carrier when they board the vessle/plane, knowingly or not. A pax would usually expect that they shall arrive at their destination alive and their well being relatively unharmed. Now when a take-off is aborted not once but twice, it poses as reasonable doubt in the mind of the pax. The problem might not have been a big issue with flight safety itself, but no pax should be required to be familiar with any of the technical details of a commercial airliner operation. Simply, the pax trust you to get them from A to B, and if you have demonstrated twice, not to just a few pax but many of them (the J cabin), that you are not capable to do so, then ethically speaking the pax is rightul in withdrawing their trust.

Legally speaking, since I'm not a lawyer and no clue how HK laws work, I can't be a reliable source. But I know that technically there are rules for delays/cancellations that are within the carrier's control, as well as the so-called tarmac delays...but since your flight has "departed", ie, left the gate, I'm not sure how things would legally work with that, any lawyers out there, maybe?