Why we might be alone in the Universe

[vulcanlogician]

It's no evidence for anything.

The signal did not create itself; where did it come?

There are a number of alternate theories on that. A military spy satellite would certainly be capable of creating such a signal and also would not have been documented/traceable as the source. Another theory is that a distant comet could have passed into the detector's field of view. 

Though unlikely, it is possible for a comet to create the signal picked up by the detector.