Page and Manafort were already part of a counter Intel op. Flynn was likely wrapped up in the same. The agents who interviewed Flynn were not cleared to know what was in those conversations.
DC has been playing dangerous games by prosecuting people who were carrying out classified operations. Make the people who are political threats do secret squirrel shit, then threaten them with lawsuits if they oppose you.
It begs the question… If I carry out a lawful order by the President and the duly appointed staff to play spy games… Who do I contact when those same people turn around and prosecute me for those spy games? This is a bit of a problem as, technically, revealing that there was anything classified is illegal. If saying "I was part of a classified operation" is illegal, then how do I get the judge or others to dig deeper?