I knew Dr. Hynek, and he was completely open-minded concerning their being extraterrestrial life forms. He even did a cameo in the Close Encounters film because he was completely open to this revelation of extraterrestrials occurring at some point in our future.
I think we’re all “open” to the possibility, but my understanding is Dr. Hynek was a scientist, and he never found any relevant evidence that Unidentified Flying Objects were actually extraterrestrial in origin. He found more plausible evidence that sightings were more consistent with sightings of supernatural entities, based on many interviews with these who felt they had been abducted. If you have evidence to the contrary feel free to provide. Thanks.