What he actually should have done was accuse them of attempting to destroy evidence if they DID suspect something was wrong. That's actually what any officer is doing if they suggest you delete (or actually delete for themselves) images. And that is a serious criminal offence, Sir & Ma'am.
I would not have left until I was filling out the 5 page complaint form either. I don't care if they've been told they're wrong and I'm right, I'd see to it that they'd know that. The reason why they get away with it is because people refuse to take these things seriously any more. Much like image theft on the internet, people think they can get away with using a stolen image by claiming ignorance and they think taking it down solves the matter. No it does not, you were using it for xxamount of time, you should pay for that usage.
Ruddy softies, meh.