You keep referring to a legal document, as if it's the legal document that matters.If we're making arguments about what the UK government can or can't do, it is the legal documents that matter. The rest is a matter of political judgement, obviously with significant implications, but it's not a binding constraint.
How can there be equality if Irish nationalists in Northern Ireland face a border when they go south, but Unionist British nationalists don't face a border when they go east?
I think you're stretching the intent of that clause. Clearly there isn't equality with NI being part of the UK but not part of Ireland either, and that's a much more fundamental difference in governance.
Do you think putting a hard border between NI and the Republic constitutes a change in the status of Northern Ireland without a consent of the majority of its people, against the legitimate wishes of people in Northern Ireland and a majority on the island?
Again, I think you're distorting the meaning with the selective quoting here. The change of status refers to the previous wording, which is about the right of the people of NI to determine whether to remain part of the UK or to become part of a united Ireland notwithstanding any overall majority on the island of Ireland for reunification.