The Immigration Department is not a collection agency
Two certainties in life: one day you will die and the taxman will get you.
The law in HKG was changed some years back when the courts decided that Immigration Department acted unlawfully in acting as an agent for revenue department by stopping someone coming into HKG who owed salaries tax. Since then they have stopped doing it.
So you'd be safe coming through immigration but don't rest easy in the belief that revenue department won't try and get you, because they will.