Upon reflection, I don’t think we should do it. What if the devices are traced back to us and we are exterminated or enslaved or simply demoralized? Let’s stick with those moons of Saturn.I've always found this argument pretty misguided. While it's obviously true that space exploration carries the risk of alien obliteration, this is not decisive because not exploring space also carries the risk of total obliteration.
The pull towards some crude precautionary principle in space exploration is understandable, but simply put: if we stick around on spaceship earth long enough, eventually some asteroid or catastrophe will wipe us out. Unfortunately we face dual existential risks whether we dabble in space or not.
Now, the probabilities involved in both of these scenarios are so miniscule that any sort of practical expected value calculation to inform a policy agenda becomes a little ridiculous. Even decision theory tools like minimax regret are problematic.
In my view, the most prudent course of action is to aggressively work towards establishing sustainable, modular space colonies as insurance against earth's eventual destruction--the truest interpretation of the precautionary principle is in fact proactionary.
This means seizing any and all small advantages and technologies that will help speed up our space colonization, including the cultivation of attitudes towards space and science that enable greater funding and policy support. This Alpha Centauri project is clearly a longshot, and perhaps taken in isolation it would be wise to avoid it given the risks; but projects like this help foster a social enthusiasm for space and increase its issue salience. I say fund it.
Highlighting the risks of action is contrarian and fun (aliens!), but it necessarily discounts the risks of inaction. Since we have no real idea when or how the earth will ultimately die--only that it will--our focus should be on the relentless pursuit of the only option that guarantees long-term survival.