There are too many reasons supporting Naruto having RSM vs him not possessing it. Simply because it wasn't shown in the Animation doesn't mean he can't use it.
Yes, it may have been more practical if he had, but it could also have backfired badly on the movie, which started its production long before Kishi revealed Naruto's RSM forms in the Manga.
No, authors don't reveal designs that early, even to animators - there's too much risk of leaks, especially in popular works like Naruto.
Moreover, he DID use Rashenshuriken - it was even shown in the Trailers. And he did so SINGLE HANDEDLY.
