I disagree with the stated assertion hat your belief is one shared by "every", or even "most" qualified defense attorneys. I don't see how you are qualified to make that claim.
Second, "he said she said" does not present a realistic threat of perjury. Most attorneys with criminal experience are aware of this. I have literally never seen perjury come from simple contradiction by another person.
Third, perjury traps are setting someone up, in an interview purportedly about a recent event, to contradict assertions they had previously made about an unrelated set of events. Not he-said-she-said. It's possible that you're aware of this, but it isn't apparent from your posting.