They have never done anything to prove that they see this country as their home. Actions speak louder than words.
Anyone that leaves without the intention to come back has a stronger connection to the place that they've moved to than the place that they've left. That is just fact.
Someone that moves here and builds their life here has a much stronger connection because it is their choice.
They may say that NZ is their home, but they are lying to themselves and to others.
You can only take actions and not what people say into consideration.