Yes, the person in charge admitted to intentionally giving my passport to another passenger. There was no admission of a mistake, sorrow, regret or human error despite several rounds of questioning and many opportunities to make a concession. This was a purposeful omission. A reasonable person who made an honest mistake would admit it. Maybe they were trained to not admit fault regardless of what happened. This is a common stance in some legal circles.

Let's just say, there is a reason why certain people have certain roles. As has been mentioned, the smarter person would have taken the details themselves in a more secretive manner. But maybe there was malice involved - that cannot be ruled out. Hanlon's razor notwithstanding, your term "dense criminal" is not unlikely.
Think about what would have happened if they had damaged the photo page, or any other page..... think about why that would or should be different.