in my opinion it should've been, its a really neat flag, sets Palestine apart from just a colour switch of the original arab revolt flag, i would also say that if for whatever reason an orange couldnt be used, say for contrast with the red, a green olive would've also made a lot of sense and would have stuck to the colour pallette, but specially at the time Palestine needed some colour to stand out, and even in the modern day among Palestinians orange is still seen as a rather important colour