I had problems with that story. Why would she risk dumping the anthrax at the doorstep of the palace which was surely guarded?
I don't believe it either. Even if SOME were destroyed, its hard to believe that, under voluntary and un-observed conditions, that ALL of it was destroyed.
One reason to continue to lie? Well, if a small sample could be located, it could be tested, and it could be determined to be the SAME anthrax used in the US 9/11 aftermath attacks.