Unless for emergency/flight safety reasons, I suggest it is a dangerous precedent for pilots to overrule/disregard ATC instructions in
controlled airspace of any type. There needs to be
some order,
some system or it'll be more than pilots egos that collide
At face value with limited info, it sounds like a very last minute call by the controller, which the crew anticipated and interpreted
incorrectly, compounded by a scenario of apparently negligible danger that added to their sense of security.
Just my 2c. Will be interesting to see what results, but it needs a systematic review of both ATC procedure or Air Maroc procedure to ensure the next GA isn't because of a 747 on the piano keys.