Because her statements on this matter - his visit to MC most specifically - are corroborated by other evidence. This thread is filled with evidence - from me and others - corroborating his visit there. What more can be produced?
As to the details such as he was going to Cuba and then (somehow) get her to join him; that's just her claim. We have no way of verifying that. So we can accept or reject that since we have no way of corroborating it.
In any case, I don't believe ANY eyewitness accounts by itself unless they can be verified or corroborated. I thought all sides on this matter agreed on that if nothing else?
Question: Why do you believe Azcue's account that the person he met wasn't Oswald? Or didn't look like the Oswald arrested for the murder of JFK. What corroborates his claim?
Steve M.,
Problem is, the source of some of that "evidence" is the KGB.
Regarding your question about Azcue, have you read any of my many, many posts here and at the EF and on my sorely neglected (by me) Google page "Jumbo Duh Is Full Of Beans" ..... on Aleksei Kulak (FBI's FEDORA), Oleg Brykin, Guenter Schulz (FBI's TUMBLEWEED), Valiery Kostikov, Ivan Obyedkov, and ...
"The Blond Oswald In Mexico City" (KGB Colonel Nikolai Leonov)?.
If you had, highly intelligent guy that you are, you would already know the answer.
.
Hint: Google
"blond oswald" and leonov simultaneously, and you might even try googling
byetkov and
obyedkov simultaneously .
-- MWT

PS Please bear in mind that my theory regarding these characters has been an evolving one.
PPS Have you even read Azcue's HSCA description of the "Oswald" he dealt with? The only thing he forgot to say was "short' (which 5' 3.5" Sylvia Duran did remember to include, btw). LOLhttps://history-matters.com/archive/jfk/hsca/reportvols/vol3/pdf/HSCA_Vol3_0918_2_Azcue.pdfEDIT: Funny thing, Azcue says "Oswald" was wearing a Prince of Wales suit, and in some of the clearer photos of Leonov taken while he was interpreting for Khruschev and Castro in the USSR, you can see some Prince of Wales-like stripes in his suit jacket.