This used different words but has the same meaning and the same lack of justification. You don't just discount eyewitnesses because they eye-witnessed something you didn't expect.
" Or, I could have just as well used another, more classic figure of speech: “extraordinary claims require extraordinary evidence”."
This careless cliche also lacks justification. Extraordinary claims require only ordinary evidence, just like any other claims. Using evidence, follow the possible chains of necessary and sufficient causes and effects, and see where they lead.
"Cui bono?" is always a good question. Everybody has heard of bizarre mothers who inflict harm on their children for publicity, sympathy or attention in "Münchausen by proxy." That would be one line of inquiry.
But it's not at all clear why professionals would put their own credibility on the line by giving positive testimony of what they'd seen, especially as it is outside of their education, training and previous experience.
It's also unclear how they could have engineered the wall and ceiling-walking of the 9-year-old boy without extensive prior preparation of the room with hoists and pulleys or magnets or whatever, and without the connivance of the hospital. Again on the basis of "Cui bono?" ---that could be ruled out because hospitals don't benefit from the public perception that they have onsite demonic activity.
Extraordinary claims don't need extraordinary evidence. They just need evidence. Would you expect to find evidence of hospital collusion?
If you want to believe everything that someone says they saw, with no corroborating evidence, then that is your prerogative. Some of the rest of us require a little more verification when the claims are spectacular. If you can’t understand that, I’m sorry, but that’s just the way it is.