Once again, he was just saying it can't be both. He never was said don't look into, do research into it, or anything else. He never made a position that is to stifle anything. He just said you can't call it unidentified and then say it something. By doing that it can no longer be unidentified. Period nothing more. It is either unidentified or is identified. A strange light in the sky can't be a plane and a UFO at the same time by the definition of a UFO. You can say "Hey, it's a UFO wonder what it is?" then proceed to eliminate possibilities. At some point you will come to the conclusion that is a star, planet, plane, meteor, or something unknown. If it stays unknown then that is all it ever should be, a UFO. Does this mean you need to make the leap to alien origin? No, because once you say it is something it can't be classified as UFO?
I am not trying to argue against alien spacecraft. I am just saying that the term, UFO, can't be used interchangeably with alien spacecraft.