If the object were truly spinning as they claim wouldn’t the tails show curvature as they emanate from the object?
Depends on the spin rate. It if takes 20 hours for a rotation and the asteroid is traveling thousands of miles per hour, you might not see any curvature over that distance. Of course it could also be the out put of a directional rocket steering it into the path of Planet Earth. That is always a possibility in this universe.