I saw an interesting post by an astronomer on Reddit that spawned a cool discussion about lots of things that make this seem like a spaceship. Amongst them were 1) the lack of dust and 2) the fact that it's weirdly long. The latter point would be explainable because at any significant fraction of the speed of light, even tiny particles in space can inflict massive damage. Making a space ship long and putting the habitation at the rear gives you maximum protection.
Still, it's cold, tumbling, and not travelling at a significant portion of the speed of light. Still and interesting object, though :)