So apparently he failed to prove that Hong Kong was his place of permanent residence. Huh? The kid clearly has no other home so how can it NOT be his place of permenant residence?
What kind of visa was he on? He couldn't have been on a DH visa because he couldn't (as a baby) legally work. And the DH visa is the only one that does not confer permanent residence.
Ruling doesn't make sense to me on a legal basis.
I have no problem with differential laws - particularly if people make choices to come here and know the consequences. But you don't choose where you are born.....