I'm flying the triple seven, though not for Saudi.
Our company adheres to Boeing procedures, which say that the T/O-flaps should be set before taxiing, unless the taxiways are contaminated with slush, in which case you should set them before entering the takeoff-runway.
In any case, the electronic checklist on the 777 includes the takeoff-flap setting and will not show "green" if the flaps aren't set accordingly.
Also, you would not be able to engage in TOGA-mode, and you would get the takeoff-config warning, if you tried to go anyway.
So whatever was the case (whether the pilots forgot to set the flaps or deliberately chose not to set them yet), this is not dangerous. There are several safety gates.