Like you said, open to interpretation. That's someone's idea that the Enuma Elish, a babylonian creation myth, in its describing the god "gaga" is actually referring to Pluto. However to believe that is what they meant - you have to think they believed "Pluto" was once a moon of Saturn that broke from its orbit and ended up where Pluto is.
Seems like a real stretch to think based on this story they believed the astronomical event above happened.
Here is the Enuma Elish; in its regular form. A tale of creation.
http://www.sacred-texts.com/ane/enuma.htm
Example:
"Ansar opened his mouth, and
Unto Gaga, his minister, spake the word.
"O Gaga, thou minister that rejoicest my spirit,
Unto Lahmu and Lahamu will I send thee.
... thou canst attain,
... thou shalt cause to be brought before thee.
... let the gods, all of them,
Make ready for a feast, at a banquet let them sit,
Let them eat bread, let them mix wine,
That for Marduk, their avenger they may decree the fate.
Go, Gaga, stand before them"
...
"Gaga went, he took his way and
Humbly before Lahmu and Lahamu, the gods, his fathers,
He made obeisance, and he kissed the ground at their feet."
There it is. This is Pluto?!!!