When they run out of things to do with Shredder, his entire part in the movie is cut short by them putting him on ice just so he could be saved for another movie. At least when Han Solo was put on ice, it was at the end and served a purpose. When the writers froze Shredder, it was them being lazy.
Hanna-Barbera WikiI hate TMNT: Out of the Shadows. All it does is play on 80s cartoon nostalgia and a trailer for an unmade third movie. It's a horribly written movie. But I do like Mikey's arc of wanting to be accepted by the top world.