I think you are underestimating what GHD is. Growth Hormone Deficiency complications are quite severe. It doesn't just make you smaller than average. Your hip bone gets displaced, your joints hurt, you have chronic fatigue, you have a risk of breaking bones etc etc.
People saying person having no arm is qualified for Singapore Military Service, yess because that's a person who lost it's arm, while still having normal hormones and continuing to have normal hormone levels.