is this innocuous or does it have hints of child abuse like the whole loli anime scene?
You should be able to stream with an anime character of any body type you want, especially if it's your original character and you commission the art yourself, as Saba did. It's fantasy. When you choose your animated avatar's body type, it could match your real body type; be an aspirational body type you wish you had; or be a business decision responding to what kind of content has viewer demand. Who cares?