An angry Shen Mu wasn't actually angry, but rather, extremely excited. He had been excited since he bolted into the canteen because the component Ji Xinghe had repaired had passed inspection. So he had hurried over to share this great news with Ji Xinghe, leaving Su He far behind in his haste.
Upon entering the canteen and realizing what Ji Xinghe was doing, Shen Mu became even more excited. He was about to rush over and start shouting, but suddenly stopped in his tracks. Standing there, dumbfounded as if a fool, he saw that the lieutenant officer, who Ji Xinghe was inspecting and who might outdo him for the chance to become Ji Xinghe's second disciple, was a cripple.
It is virtually impossible for cripples to come to an alien planet, let alone become a Mecha warrior. The spotless, brand new prosthetic leg spoke volumes about its recently equipped status and the fact that this Mecha warrior was not originally a cripple.