Surely the main issue here, ignoring 'why and how', is that the crew refused an ATC instruction 3 times. This is not acceptable. There were no 'safety issues' which would have been raised by obeying a lawful command. There was no justification for disobeying.
Quote from the ?'transcript'?
"07:34 ATC: "...except when I instruct you THREE times to vacate because there is traffic behind you".