Why Gov rejecting the right of member state in UK

During some finding i came across this document from the house of common library and i have no doubt why
UK doesn't want to give any assurance to all EU AND ANY FAMILY MEMBER IN UK.

Please you may just read the paragraph 3.4 it's quite shocking.

http://www.parliament.uk/briefing-papers/rp13-42.pdf

I am not sure precisely what you find so shocking about that specific section of the document.

Firstly, it is a briefing by the Commons Library, which is a non-government independent body that does impartial research for MPs of all parties.

Secondly, its states the opinion of the EU Commission about what the status of EU citizens in Greenland would be when Greenland left the EU. But that would be one opinion, and not the final say, on that matter.

Thirdly, the role of general international law and its involvement with individuals as opposed to nation states and their national governments is nebulous. General international law creates obligations and rights at national level and not at individual level.

And finally, there is every chance that the status of the EU citizens will likely be protected in any negotiations. What is unclear is the status of their non-EU families and people like Zambrano carers, whose have rights under EU law.

As I have mentioned elsewhere, given the size of the corpus of EU law in effect in the UK, the UK will most likely pass a stand-still law that will retain all EU law as of a specific date. But it will then become domestic UK law that can be amended. And given how influential an issue immigration was, that will likely be on the top of the list of post EU laws to be amended.