It turns out the three individuals are more or less the usual suspects--well known Deep State actors who have long since either outed themselves or have been exposed by investigative reporters. Of the first two,
John Sipher, was a member of the CIA’s Senior Intelligence Service. He wrote an article in September 2017 where he claimed the dossier was reliable.
We know that Chuck Rosenburg was disgraced former Jim Comey’s Chief of Staff.
The third person, former FBI agent Anthony Ferrante, was exposed in an excellent investigative article by Paul Sperry, which we covered in Sperry's OIG Bombshell: Comey Targeted Trump. At that time, July of 2019, Sperry reported that Ferrante--who had been detailed to the NSC essentially as Comey's spy within the White House--left the FBI in April, 2017, and
"contracted with BuzzFeed to lead the news site's efforts to verify the Steele dossier, in connection with a defamation lawsuit."
In other words, BuzzFeed paid Ferrante to say that the Steele "dossier" was legit because BuzzFeed was being sued for having published it. BuzzFeed paid to rent Ferrante's supposed credibility as a former FBI agent.
What's new is that Chuck Ross quickly responded to Orbis' self serving tweets with this:
Chris Steele's firm published a letter to the editor suggesting that ex-FBI official Anthony Ferrante had validated the dossier.
The firm did not disclose that a.) Ferrante did not validate the dossier, and b.) BuzzFeed paid Ferrante $4 million to try to do so. pic.twitter.com/YeBnHXNZVG
— Chuck Ross (@ChuckRossDC) February 25, 2020
I assume that Durham is checking all of this out, too.