Why? They famously forgot about NI in 2016. We did NOT vote to split the UK
Monarchs had divine power, which was limited by consent
Brexiters cannot behave like divine monarchs, stretching definitions of consent infinitely or saying consent was given by omission
"No Deal" meets NO reasonable test of the mandate of 2016, as you can see in this thread. In which case No Deal is NOT Brexit and is NOT compliant with Article 50.
Cummings quotes are useful as cast-iron public documents written by a source who cant be argued to be a secret Remainer.