I should have known better of course

I should not bother to comment. 
There was that very nasty incident in the New Zealand parliament yesterday with the comments about rapists and murderers and who supports them and... I won't bother to try and sort out the horribly tangled mess. I suspect that, in the heat of the moment, all sides said things that they were sorry they said and that some things were misunderstood.
But, if you are living in another country as a guest and you have not bothered to take out citizenship when you could, then shouldn't that country have the right to deport you if you commit a serious offence? If you were a guest in someone's home and you started to deliberately damage the house or hit their partner don't they have the right to tell you to leave?
Yes, there are people who have lived here for years. They have grown up here. Their family are here. They have no ties to the country of their birth. Deporting them does seem very harsh. It is a punishment over and above the one handed out by the courts. It is treating some people differently from others. 
The question still remains, why haven't they taken out citizenship - particularly when most countries allow dual citizenship. They wouldn't be losing anything. They would be gaining something.  If they don't do this then it would seem to suggest that they have, at very least, no respect for the place in which they are a guest.
I don't know what the answer is. I suspect it varies from case to case. 
But, I was foolish enough to suggest that perhaps the best place for rapists, murderers and the like was on an uninhabited island somewhere. Now that was clearly not a suggestion to be taken seriously for any number of reasons. It was meant to show that there are people Downunder no longer wants as guests and that, in this instance, there are Kiwis who would not be particularly welcome back in their own country. The idea of putting them somewhere else, somewhere nobody else lives, might well be attractive to some people. 
If some people find that offensive I am sorry but even I can think of a handful of people I would like to place on an island as remote as Pitcairn - without internet or other broadcast access. The world might be a better place.