You can question the truthfulness all you want.

It doesn't change the fact that this has been a well established aspect of the language struggle in Norway for well over a century, to the point that when I went to school it was even covered in history lessons.

I'm mystified with how you are ignorant of this. Bokmål has it's origin firmly in being derived from Danish via Riksmål, as based on how the elites spoke.

The spread of Bokmål was a direct consequence of its prestige as a consequence of for a very long time being the favoured written language of the elite, leading to adoption even in areas where the spoken dialect was closer to Nynorsk.