"When it comes to a critical element of Brexit ie NI, you seem to abandon those principles in favour of some blanket coverage."
Te democratic will of the majority who voted was to leave the EU. The democratic will of the people of both the UK and Ireland is for there to be no hard border in Ireland. There is no reason whatsoever why both these wishes cannot be accommodated. There are no democratic principles being abandoned by facilitating those wishes. Quite the opposite, in fact. If they are not accommodated then the will of the people (which is, after all, the very essence of democracy) will be ignored. And it will be ignored because of the intransigence of an unelected bunch of foreign civil servants who see the wishes of the people as a threat to their ideals.