Wow, I just picked up on this now.
Rutkowski: After all these years, how do you respond to the critics who are hammering away, "It didn't happen"?
Walton: It kind of depends. Some of them can seem like more of a threat because they actually have something to say. But so many of these are without substance.
So as you pointed out; if the concern has substance it's a threat. A threat to what? The irresistible inference is that if the concern has substance it threatens to discredit the story.
"There is the endeavor to deflect any suspicion from himself, to efface all traces of the crime, and an impulse
growing more and more intense suddenly to cry out his secret in the street before all people, or in milder cases,
to confide it at least to one person, to free himself from the terrible burden." -
The Compulsion to Confess