Instead of saying 'yes I did"... someone wonders if a triangular tablet could be built which unfolds into a square display, like the triangular notepad in the article which unfolds into a square notepad.

They parent replies that nobody would want triangular tablets because of the waste at the corners when drawing square shapes, and the well-known rectangular nature of existing displays means nobody would jump at developing triangular UIs. They completely missed that the point of the triangular notepad is that it unfolds. That implies they didn't look at the article, because it has a picture of the triangular notepad doing that.