While I often take gear out in below freezing weather, I would not / do not store backs in the freezer. First, I don't know what long term exposure to freezing temps will do to soft plastic or rubber components. Second, ziplocs are not airtight (they are air permeable) so you are subject the equipment to the very low humidity in the freezer. Third, there is too much risk of condensation on internal components when exposed to more humid air (though this can be significantly minimized). All in all, I just don't see it worth the risk just to save some film. I would use the film up or, if loaded but not exposed, take it out and re-roll it.
Just my 2 cents. I'll defer to someone who has actually done this multiple times and can report on results.