I was adding to the original posters comments that "either he saw it, or he didn't." There are other logical things to be added to that list... "he saw it and lied" or "he didn't see it and lied." These also should be included on the list of things to be tested for.
As to being skeptical. I am convinced that UFOs exist because of personal experience. It is very difficult to be skeptical when one has, along with other witnesses, SEEN a classical flying saucer shaped UFO that displayed unnatural flying patterns under circumstances that could not have been faked or caused the witnesses to mistake what they saw.
You are so gullible that you believe that little alien spacemen landed in the woods in England no matter what the evidence (or lack thereof).
I found it highly unlikely he was even consciously or unconsciously distorting things very significantly and far to ridiculous that he would be lying.
But you find it more likely that spacemen landed in the woods in England and there is a large agency of "men in black" who will come and inject you with mysterious chemicals to alter your memory. You also have stated that "millions of people" have been abducted by alien spacemen. Apply Occam's Razor.