You see, as I am an aircraft maintenance engineer and marshall aircraft as part of my job, I have never done an emergency stop using that sequence. My emergency stop is the 'stop' signal quickly followed by the brakes on signal.
It's not as if we invented that gesture: the images and the descriptions on the manual are taken from official training documents. Now, what people do in real world might be different, I've seen many videos of marshallers doing what should be the most standard gesture (the "Straight ahead") using *entirely* different styles, but of course the program should stick to some kind of standard.
The only thing that might be argued, is the numer of repetitions the "crossing wands above the head" animation will get, but it's surely a repeated movement, as indicated by the two-pointed arrows, meaning it will made at least once up and once down. We made it so it will repeat more times, because in a simulator on a PC screen, it's easy to miss things compared to real world visibility, to be sure people will not miss it.
As you might have noticed, the marhsaller will ALSO do a small step ahead with his foot when doing an emergency stop, and this is also made intentionally, in order to have the gesture more noticeable, and differentiate it better to give the impression that something that required more attention has happened.
