I'm deeply sorry for you experience and I think you have made your points. May be they thought the last flight was able to make it because in the boarding usually last about 30min and this time, all PAX were at the holding area. I believe they are also trying hard and cracking their brains to send the delayed PAX back to HK but given the amount of work in hand and the non-stopped updates of the worsening of the situation, they were overwhelmed...