With very few exceptions, airports in the US do not have a concept of sterile cross-border transfers for international passengers in transit. This basically means all passengers arriving from an international destination must enter the United States and be processed by US Customs and Immigration immediately upon arrival. I know for a while, they were letting passengers on the SYD-HNL-YVR operated by Canadian Pacific and then Air Canada stay in a sterile gate area during the HNL layover, largely because it was very late at night and the connection was relatively short so they didn't want to staff up enough to process a few hundred people. So, I would assume your parents would have to exit the flight in HNL, pick up their luggage from baggage claim, enter the US, and then recheck their luggage with HA and re-clear security to get to their departure gate.

As a US passenger, you wouldn't be able to see your parents until after they've re-cleared security.