She didn't meet their technicalities. In fact, she is not even truly Aes Sedai. That is ALL that counts with them. They call her child, because she is an initiate and not a sister. Recall how when Siuan and Leane were Healed they said that being as weak as they are is worse, as far as dealing with the other sisters are concerned, than not being able to channel. If Nynaeve could not channel, they would be talking to her like a normal woman. But because she is not an Aes Sedai, of course they are going to treat her that way. What is her claim to the title? Only Egwene's authority, and Merise's response to the rebel Hall was the best position I have ever seen any sister take on the situation (except for Nynaeve who isn't really loyal to the Tower). This was not irritating to me in the least, because it is perfectly consistant with the Tower's attitude, past behavior and my low opinion of them. Even Sts. Verin & Moiraine had it and expressed the attitude in the past of the inherent inferiority of channelers who were not Aes Sedai.