Lawyers like you and I know better, but I've seen high level corporate executives answer questions in potentially incorrect ways because they just assumed a number of facts, and didn't bother to provide any caveats. Thankfully for them, I was there to prompt them to fill in the gaps on their assumptions, to clarify the record. Flynn didn't have that advantage. If one of those assumed facts turned out to be wrong, then the executive could be charged with "lying"...at least, if they worked for Trump's campaign. If they worked for the Dems, they would not be charged. If they want to, they can remind the interviewee of their obligation to tell the truth, and the penalty for not doing so...if they suspect an accidental incorrect statement, they can follow up to get the facts...or not, if their main goal is to get a prosecution for a lie rather than to actually get facts.