He isn't being particularly consistent. Like how a couple of days ago saying Aaron lied about losing his phone but then also said it would be a crime to dispose of evidence. Both couldn't be true.
Now here we are again. Nick isn't clear on what he claims. He could be saying they got a copy of the messages from Aaron's phone, but then in other messages he is making a big thing about Geno and Keanu previously admitting on video they had seen the photo, which would be an odd thing to focus on if the prosecution really had the messages.
I'd suspect, but could be wrong, Nick conflates multiple things to try to make people believe the case is stronger than it is. The word "Imperative" was used on the subpoena form. This doesn't sound like they have an expert witness that can testify without Geno's testimony.
It's fun to watch though.