Disclosure: I don't believe the Buzzfeed story as reported.
However this whole thing around the story is intriguing As others have said - Mueller didn't 100% discount the story. The wording is very specific. For Cohens part, he and his lawyer also aren't saying its false. They're not saying it's true either, preferring not to comment.
Buzzfeed News pushing back against the special counsels office and asking them to clarify is a fascinating play. I'd say asking the Office of the special counsel to clarify anything further is about as effective as squeezing blood from a stone. They aren't talking.