It would be easier for the Earth to colonize Mercury than for Pluto to colonize the Earth's Moon. On Pluto helium and hydrogen are liquids, most the rocks are nitrogen with occasional outcroppings of igneous oxygen. Water would be their equivalent of steel. Even deep underground the average temperature of the Moon is such that it would be like us living in the throat of an erupting volcano. Plus the Moon has a surface gravity greater than 2x Pluto's.
The best thing to do if we found them trying to colonize the Moon would be to make contact and offer to swap our labor for their scientific knowledge. We would not be able to replicate or use their technology except outside a cryogenics lab.
What we should do is invite them to address Congress: h**p://en.wikipedia.org/wiki/File:MartianUS.jpg. If they get outta hand, we open up with Slim Whitman . . .
At least according to one of my favorite campy movies.
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