Yup, there is absolutely no meaning behind this child's posture (or the look of admiration beaming towards him from behind).
It has absolutely no history or significance at all.
Nope. Meaningless. It definitely doesn't imply that anyone is rooting for Islam or Islamic-related terrorist groups to achieve a "Victory" over any Western powers.
In fact, I'm positively positive that he's not doing this because he's been taught to hate non-Muslims.
That'd be downright silly.