The problem with your argument is that there are already hundreds if not thousands of alien abduction reports.

(They probably didn't have turnips though, I hope that wasn't the point.)

The problem here isn't whether this is scientific evidence, but that the evidence isn't sufficient for scientists to form a reasonable hypothesis about what gives rise to the phenomenon (which could be (a) aliens are real, (b) some form of mass hallucination, (c) some form of synchronized fraudulent claim, (d) etc. etc. ).

I speculate that if somebody actually does a "literature review" of abduction reports they could pick out some signals to form some hypothesis, but presumably scientists have better things to risk their careers over.

But crazy carl saying his prize turnip was stolen by aliens ISN'T evidence that his prize turnip was stolen by aliens, it's evidence that crazy carl BELIEVES/SAYS his prize turnip was stolen by aliens.