I’m pretty tall and I’ve never experienced or seen others experience difficulties like that. You just use your waist and exert a lot more power that way. Balancing and posture are only an issue when you’re still in your growth spurt and not used to your new height yet.
The picture is kind of small, but seems to me like he’s not using his hips properly for leverage. It goes a lot faster and you have to bend less when you do it that way. A shorter person can’t do that as well and depending on how short they are (the trait to me implies very short) they would end up exerting significantly less force, because of being unable to pull the string as if lifting it and therefore having to rely on their arm strength.
