I think the origin was meant to be affectionate, and Xi is not just shorter but a bit more stocky while Obama is lanky, so it’s an exomorph/endomorph thing.

I disagree with the original usage because Obama is a monster, and the fucks using it in the anglosphere are using it because racists latched on to it and a certain racist caricature using Xi and the bear, but the original use was intended to be positive.