Awesome question! I definitely laughed.

The serious answer that the GitHub link clarifies is that the model is semi-unsupervised. That means they have a lot of data, but only some of it is labeled. Presumably, the labeled data is all negative because we understand its natural origin. So effectively this becomes almost an anomaly detection sort of thing, looking for data that is least like the known natural signals.

Even if it just directs scientists to look at new natural phenomena, this sounds like a valuable task.