On the surface this might seem obviously wrong. Egwene's the Amyrlin, enforcing the rules of the Tower is her jurisdiction, the Oaths and sisterhood fall roughly into that category, QED. But then there is one of the few issues on which she has been right - the inviolability of the status of an Aes Sedai. Elaida was absolutely wrong to decree Shemerin stripped of the stole. The status of an Aes Sedai once conferred is a general acceptance by the White Tower, and NOT a gift to be handed out or taken away by the Amyrlin Seat, even if she has final approval over the granting of that status. As an issue of the Tower, it can, or should, only be issued or revoked by the law of the Tower, and not any particular individual's whim.

The only problem with that position, as related to Nynaeve, is that ship has sailed. Nynaeve is already Aes Sedai. That was not made conditional upon her passing a test or taking the Oaths, it was simply stated and asserted and, with the Amyrlin's full support, was held to be every bit as valid and equal as any other sisters' status. Nynaeve was made a full Aes Sedai, absolutely and unconditionally, and retroactively attaching conditions to her keeping the shawl and title is absolutely no different than Elaida revoking the shawl from Shemerin or demanding the sisters swear an additional oath.

Some might claim that the particular nature of the Oaths is an issue, but that was not the problem with Elaida proposing a fourth oath. It does not matter what that extra oath is, and an oath to serve the Amyrlin Seat is no more immoral, wrong or absurd or even contrary to any principle than the first three. The wrongness with what Elaida proposed was of a piece with her assumed right to remove sisters - Aes Sedai ARE, and Elaida, or any other woman, has no right to go around attaching conditions to retaining that status. Which is also why Elayne was wrong to confiscate the great serpent rings from the Black sisters she caught. What Elayne was doing was an act of denial - she was trying to remove their claim of association with the Tower and with Aes Sedai. While her motivation was probably more horror and disgust at them, than any attempt to cover the Tower's ass, she was still doing the wrong thing, and something on the order of vigilantism - the cops chase vigilantes not to protect criminals but to enforce the law even-handedly. Elayne's act is as wrong as the perfectly natural impulse to slap around a handcuffed child molester.

The problem with the scenario as far as Nynaeve went was the presmuption of her inferiority because she did not take the test, but there is no reason she should have been able to tell them where to shove their Oath Rod. She was already Aes Sedai. She only took the test to prove to everyone else that she could do exactly what they did. Unfortunately, Nynaeve has always cared too much about what other people think about her and thus allows the opinions and condescension of people she knows to be hidebound & inept fools to bulldoze her into going along with a violation of an important principle of the White Tower. And piss away one of the last best chances left to rid the Tower of the Three Oaths as well, but that is another issue.