As I said before, they are not above the law, but they have different rights, authorities and responsibilities under the law when on duty.
I'd love a bit of whatever you are smoking.
According to the SCMP, the guy was Nepalese, a HK resident and had numerous convictions for assault and wounding. He might well have gone after the cop if he'd tried to back off.
The cop did his job, I think it's a justified use of lethal force.