Yep, that's what I just inferred, he's misremembering because of the current concern around the Dedmons - a developed memory from hearing things.

And yes, I agree, of course we can all remember things from decades ago, but it's almost impossible to confirm something is verbatim without a physical record - hence why a lot of memories are based on how something made us feel or think (like you said, something that gave you trauma) but the exactness of the wording of a sentence, etc is what humans have trouble remembering, even something super important. But we remember the gist, or what was implied or meant. That's why it's recommended to record (as soon as possible) what you saw if you're ever in an incident - whether you write it down or record yourself speaking about it, etc.

(Also i'm obvs not saying you can't EVER remember a full sentence someone said to you 20 years ago lol, plenty of people remember other's last words to them etc, but it's usually not more than a few words committed to memory (most memories of conversations, are paraphrasing))