This case is being waged in the court of public opinion, by both sides, independent of what the indictments actually say, is the answer.
How does the Espionage Act define “national security information?”
I don’t know that it does. But the DOJ thinks it does, and they probably have witnesses from government on their side who can attest their opinion of it. Courts are where charges and the law are weighed, so Trump would be offered an opportunity to dispute whatever info they’re talking about isn’t national security related, etc.
Actually, the first two paragraphs of the article posted above suggest that this is NOT the case.
And keep in mind that this is exactly what makes the case so ludicrous. If the prosecution and prosecution he defense have competing opinions on a point of fact (as opposed to a point of law) in a case, then the jury MUST see the evidence in order to make a factual determination.