You ARE allowed to use these on the coasters and Doom as well. I have friends who bought them and used them for that very purpose. The snapchat brand associate made it clear that they would be able to use it on those rides.
My friends showed me some pretty awesome footage he shot on those attractions so he wasn't lying. I found it odd at first too, but thinking about it, plastic sunglasses falling causes a lot less harm than a Go Pro or a cell phone. This is a way to get money out of people who want on-ride footage.