Well, in the case of that paper it's true. It's using deductive reasoning, but my statement is more easily read about inductive reasoning. However, you could equally read it, "other theories that provide predictions that contradict this reasoning". My point was be constructive and creative, not just dismissive and destructive. Have something to offer, an alternative way of viewing the world, rather than just saying "this way doesn't work".

But reading it the way you did, I disagree. We do have plenty of data on aliens. Do we have any "data" on drug-use? On parental abuse? On sexual assault? Most of these "data" are self-reported by people involved. But that's "hard data" from a public health / legal point of view.

Equivalently, we have plenty of witness data about actual non-human beings in craft. And we have plenty of data about craft that seem to exceed anything we are capable of. So we have "we do have plenty of data" not "we don't have any data at all" is what you meant to say, if you were reading the world consistently, honestly and openly.