1) Obviously, according to this theory, Mesaana had to have been someone else during the coup and the initial few months of Elaida's reign. The question then is... why did she want a new persona?

2) While it is true that Tsutama's personality has changed, it is also true that her memories will have to be perfect. However, Tsutama was a high profile Sitter. There are certain things she'd have done and said that would be well known to many Aes Sedai. How certain can Mesaana be that she knows all there is to know? Isn't it better to go for an obscure sister?

3) When the Hall decided to raise Egwene, they sent curt missives to the Reds, asking them to refrain from raising new Sitters. If Mesaana were Head of the Reds, she had an unparalleled opportunity to ensure Egwene was not elected, or at least was elected in a bloody manner. Yet, she complied with the Hall's orders.... why?