First, I think the hypothesis is something more like, “other intelligent life exists in the galaxy (or universe).” As I wrote in my essay on ID, that is unfalsifiable, hence “unscientific” according to Popper’s “falsifiability criterion.” Think about it. How could anyone possibly prove that no other intelligent life exists in the galaxy, let alone the universe?
But let’s suppose your version is correct. If other intelligent life exists, then “they will have created electromagnetic signals that should be detectable.” That is also unfalsifiable. How could anyone prove that other intelligent life would not have created electromagnetic signals?
But that is all secondary. You said, “They are searching for said signals.” That does not answer my main question. How will they know if they find such a signal? In other words, how are they “testing their hypothesis,” as you put it?
What is the ID hypothesis and what is the experiment?