There is absolutely no context for this ‘inclusion’.
“But there doesn’t have to be – it should be seen as normal!”
Yes, except it isn’t, as we are given 2 sssssllloooww shots of the fake leg, and in this second one the trouser leg drops down slooowwly to reveal even more fake leg.
If this was a standard little biped, the 2 shots would be considered absolutely mundane and wouldn’t even be used because hello – ‘boy just looks at TV’….? Does that strike you as a cutting edge idea in 2020…? ‘Boy watches TV then is teased by sister’, ‘Boy watches TV and then is waved to by character on TV’, perhaps. But just ‘boy just watches TV’ – it’s painful forced inclusion for inclusion sake. And that is treating him like a circus freak.