This kind of argument seems like it's only appealing through it's similarity to one of Aesop's Fables.

I think as far as we know, ant's don't even ask themselves the question "what is this ant hill". Human cosmologists, on the other hand, seek an explanation for everything that they see in the cosmos. The only way some alien phenomena would be ignored would be if it seemed to have the qualities of some apparently easily explained phenomena. This is certainly possible but it seems unlikely it would happen by accident - cosmology's models for ordinary, unexceptional stars, nebula and galaxies are all fairly detailed.