The problem is that science cannot prove a negative. They can only produce evidence that, to the best of their knowledge, it appears that people weren't flying, but there will always be additional questions at every level. Soon enough the research will run out of answers.

I.E. "Well, do you have records of every region of Malaysia during that time? What about every family? Maybe it was passed down in just one lineage. Can you show me the evidence you collected on every single Malay? Maybe it was just one person."

When dealing with people making obscene claims, the only sensible way forward is to require them to produce evidence of their claims or get off the proverbial stage.