So you agree that if there will continue to be an ooen Border between NI and ROI, there will also be open borders between the rest of the UK and the EU???
This comment works on the supposition that there are currently open borders between UK and the rest of EU. There are not. There is a bloody great channel in between, and even those who drive under it, or fly over it, are met by customs stations. This is, in no way, analogous to the situation in Ireland.