The article doesn't really answer the question. You wrote that meetings with the POTUS are covered as classified. All meetings? is what I'm wondering. Because, for example, if the winning NFL team meets the prez and then the players talk about it to the press, that's not classified. Take a look at what another lawyer said.
"The only way there could ever be a criminal case against Comey for leaking his memos, Vladeck told me, is if they contain classified national security information (in that case, a leak could be a violation of the
Espionage Act) or information “that has pecuniary value to the United States” (which could be a violation of the
federal conversion-of-property statute). Would it be possible to make the argument that the memo Comey leaked did contain that kind of information? “If all he did was memorialize the contents of a conversation with the president the contents of which were not themselves classified, no,” Vladeck says."