Not sure how often they may have been to Hong Kong, but with 9 hours, you should be able to get far more out of it than just the cable car and the Buddha.
For me, I would probably agree fully with
@amaroo and pay the fee to check the hand luggage (combining if you feel the urge).
I think this thread started with a reference to HLO, but then came across checked baggage. Assuming what is happening is checked + hand luggage, I would work out they actually want to carry with them (presume there will be some day pack, bag etc. with camera, passport etc.), pay to store any other hand luggage, then take the rest on MTR into Hong Kong itself. Check the bags back in at the in town check in, and then explore multiple parts of Hong Kong.
If it is clear, a trip up to the Peak will probably be more interesting than the Buddha. Even if not clear, the ferry on the Harbour is cheap and worth doing. Any number of places to visit on either the island, or Kowloon (mid-levels, Ladies Market in Mong Kok), etc.
EDIT
Saw the update after finishing. If they have already spent time in HK on the way out, that changes things a bit. They will need to check weather before attempting the Buddha. If it is too windy, the cable car won't be running.