The WaPo article you cite,  "The Quest To Prove Russian Collusion Is Crumbling" is an OPINION piece by a conservative partisan and Trump apologist named Ed Rogers.

"Ed Rogers is a contributor to the PostPartisan blog, a political consultant and a veteran of the Ronald Reagan and George H.W. Bush White Houses and several national campaigns. He is the chairman of the lobbying and communications firm BGR Group, which he founded with former Mississippi governor Haley Barbour in 1991."

What Ed Rogers says is irrelevant. Robert Mueller's investigation continues no matter what. He's not going to be distracted by spin and fake news.