[Suga00]

I passed by this post and I remembered delta's website had a part where you could enter your citizenship and destination and it tells you documents requirements to enter:



National Canada (CA)
Destination Hong Kong (SAR China) (HK)


Hong Kong (SAR China) (HK)



Passport required.
- Passport and/or passport replacing travel documents must be
valid for at least one month after the period of the
intended stay.

Visa required, except for A stay of max. 3 months to nationals
of Canada.
Visa required, except for Those entitled to travel under the
Hong Kong (SAR China) Travel Pass Scheme.(SEE NOTE 23278)
NOTE 23278: The Hong Kong (SAR China) Travel Pass Scheme
is meant for frequent business travellers
For details, click here
Visa required, except for Holders of an APEC Business Travel
Card. The back of the card must state that it is valid for
travel to Hong Kong (SAR China):
Additional Information:

- Admission and/or transit will be refused to any national
holding a passport issued by Kiribati and endorsed
N-Kiribati or Investor .

- In connection with the BEIJING 2008 OLYMPIC GAMES and
PARALYMPIC GAMES, members of the Olympic Family and
Paralympic Family For details, click here

- All visitors must hold:
- onward or return tickets, except when in transit to either
mainland China (People's Rep.) or Macao (SAR China);
- all documents required for next destination and sufficient
funds to cover their stay in Hong Kong.

Warning:
- Passengers arriving without the required documents or with
incomplete or expired documents, may be refused entry and a
fine of HKD 10,000.- will be imposed on the transporting
carrier. The carrier will be responsible for returning
passenger to point of embarkation or place of origin.




---
The attitude and treatment was wrong and unfair, but however many times you may have traveled to and from Hong Kong the airlines can not take a chance sending you into a country that has rules requiring return/onward documents.