I think we all understand what hearsay is. Recounting overheard conversations still has journalistic value. The reader will be left to decide if they believe the account or not. Given that Mattis, Kelly et al have everything to lose and nothing to gain I would expect them to disavow anything that is ever said by any third party, in any setting and for any reason. That, however, does not mean that it didn't happen. Each person should perform there own litmus test, ie. is the source credible, is it plausible, does the person have a motive to lie, etc? You know, all of the things that folks have not demanded of "Q."
I think what you're offering is a barrier so high that the only thing you'll accept is an outright admission, on camera, holding today's newspaper while holding two forms of valid ID. In that case, why are you even bothering to weigh in?