By admitting that they knew these documents were classified and did nothing they have now broken the law. If they shut up, they can plead ignorance “oh I figured it was role play, why would I trust stuff on the internet, etc”.
It is never in your interest to talk to anyone in cases like these. Get a Lawyer on retainer and wait.
Sections C through F. I'm unsure of relevant case law, it may be untested, but it's part of the charges against Julian Assange.
https://www.justice.gov/opa/pr/wikileaks-founder-charged-sup...
And trying to argue "the law itself can be used to charge people, but not the subsections that clearly apply in this case despite the lack of case law striking them down" is silly. Those laws are on the books, and being used in an indictment. They definitely could be charged, though probably won't be.