*edited to alter some wording to try and avoid suggesting Cohen had no plea at all, rather than needing to alter his plea to accommodate rather significant other cases of lying under oath*
I think a number of people from all sides of the Russia theories dispute, like marcy wheeler and some of her normal opponents, are appropriately pointing out a potential problem with the story being "the smocking gun" isn't really BuzzFeed or its reporters, it's that they've built a specific case against Cohen for specific actions, leaking stories like this and painting Cohen as a compulsive liar doesn't help their case and is actually what Trump's camp would prefer as it messes that whole thing up, and even more so messes up any attempt to use Cohen as a further credible witness. It doesn't help Cohen, sure, but nobody gives a fuck about him anymore.
It's entirely possible for every single aspect to be true, so that say BuzzFeed poorly reported on a story that Cohen told that's actually true. But even in that case, Mueller still wouldn't want it if the only piece of evidence available is Cohen yet again lying about something but it wasn't important enough to plea regarding.
This happens all the time in normal cases, down to drug dealers or small robberies, prosecutors don't want to give up a slam dunk to chase a whim in which their initial source would be a liar telling them something they want to hear not in the plea. (Again, I'm presuming that they don't have anything else currently to corroborate Cohen to illustrate why a prosecutor would avoid the case; not saying that there isn't any other evidence in this particular case. Still feel free to call me stupid, Mandark.)
