I think the real bottom lines are:

1) HX is a cheap airlines. If you pay for that price, expect the accordingly service;

2) Mainlanders are VERY after money. They would seek monetary compensation no matter whether they have the legal standing. My mother-in-law is a perfect example. She always comes up with ideas in how to get merchants to give her more, by finding "faults" here and there. In a more contract and law-oriented society, this wouldn't work;

3) Occupying a airplane is un-lawful, period;

No matter how vulnerable this "one country, two government" cover is, S.A.R is still S.A.R. It has its own jurisdiction (also controlled ultimately by the Party, through appointing the sub-boss). So whatever these Mainlanders are used to inside China, they won't get the same thing in HK. I am especially sympathetic to the people from HK, as they are on the front line, taking hits from Mainlandermanium. If similar law-breaking things happen in Singapore, these guys would be arrested anyway. That's why I think HK should firm-up its law-enforcement as well.