who was in the room is hiding in case a subpoena gets issued.
The fact that she named other people who were there, two of which regularly hung out with Brett adds to that credibility.
The fact that she first reported it before he was nominated also adds to that credibility. She called WaPo when he was on the shortlist.
Her demeanor was credible and believable.
She passed a polygraph.
Her story is credible, albeit not corroborated which is the fundamental problem.