The first reviewer might have thought it was borderline, but in your favour, and the second might have thought the same, but not in your favour. Submit it again and add a note with a link to the existing item and it should get approved.
It’s too simple to be approved as an AE project. All of the main things you can do in the AE template would be achievable by just adding content on top of, or at the end of, the existing animation… apart from changing the background. They might want to change the text by the time 2018 rolls around, but I’m sure you’ll release a new version by then.
The thing is, it doesn’t really fit into any category. It’s far too simple for a logo sting, not long or complex enough for an opener or titles, and there are no placeholders for a promo, slideshow or video display.
If it was me, I’d upload it as a motion graphics item, a png version of the animation with transparent background (without text), and bundle it with a selection of pre-rendered backgrounds and text options. You could make it some kind of kit as well… different animated elements that people can use to populate the scene… reindeer, snowmen, christmas trees, elves, the sleigh etc.