Am I right that https://english.stackexchange.com/a/96966/50720 is claiming thus (as regards the title of this question)? If so, how do you derive or explain this equality of clauses?
I'm also reminded of Edmund Blackadder being irritated by an old witch's turn of phrase, and reprimanding her:
"It's Yes it is not That it be!" http://www.bbc.co.uk/programmes/b006xxw3
For anyone who doesn't know, this is a BBC comedy programme and the line is obviously done for comic effect, but it stems from the fact that 'it be' was commonly used at one time, and might still be used in certain English dialects.
It's clear that that many kinds of 'incorrect' or non-standard usage have been around for a long time and I don't think it's up to us (we) in the 21st century to tell them they were wrong. The point of language is communication. As long as there's no chance of confusion when using Not I/Not me, it's a matter for personal choice. Let it be!
Blackadder: Tell me old crone, is this Putney?
Old woman: That it be. That it be.
Blackadder: "Yes it is", not "That it be". You don't have to talk in that stupid voice to me, I'm not a tourist.