It would have been helpful if she had said the first time she cited info Geva's bio that it had a number of factual issues, but in this case, she's given five reasons why the account is suspect.
Kendall has a tendency to question people's statements without giving the reader an adequate sense for why that person's statements are unreliable. We need to see evidence; otherwise, the author comes off badly. As an example:
"Geva wrote later that Georges's father and brother traveled from Georgia for the wedding, though this seems unlikely given the distance, the ruined railways, and the Georgian Balanchivadzes’ poverty. And where were Georges’s mother and his friends in a school chapel wedding? No one has left an account of it except the bride. Georges’s friends heard about it only afterwards; they’d barely known about Geva.
But for Georges, who did not advertise psychic events, this mariage was an ultraprivate affair, and in private terms a masterstroke."
Why state that the marriage was "ultraprivate", but then question why there were few witnesses?
Could she have meant that "ultraprivate" to Balanchine meant that he wasn't interested in talking about it? In the Taper, it was clearly a marriage to address troubling times: even though they were a couple, they were very young, and they'd not have married then in calmer times.
Geva is not Kendall's subject, and even if she had been, there's enough psychoanalyzing in biography. If a bunch of what Geva wrote in the memoir is suspect, why would the reason for this be something for which Kendall owes an explanation? If it were the only thing in Geva's memoir that was suspect, but Kendall had contrary evidence for it, Kendall wouldn't owe an explanation for that, either.
So we should assume that Geva needed to lie about her wedding details? Sorry, why precisely? (Or is that being saved for Kendall's next book?).