Because Egwene all but directly threatened her and Elayne with "Tower justice" if they persisted in claiming the status she granted them. Her words to them are exactly as bad as the crime of demoting sisters for which she excoriates Elaida. Egwene granted them the shawl. She did not make it conditional on the Oath Rod or anything like that, and while she may not have made an overt statement of this, her mindset at the time was opposed to the Three Oaths. To later demand they fulfill a condition to retain that status is every bit as wrong as Elaida's assumption of the right to revoke said status as she pleases, and a violation of the exact same principle.

And as for the ad hominem attacks, I do not even really make an issue of this or agree with the original poster blaming that on Egwene. It was all Nynaeve's doing anyway. Nynaeve is great on the actions, but can be kind of short-sighted and not too clear on the fine points of principles.

I hold out hope that Elayne's refusal will in some way lead to the eradication of the Oaths or at least the Oath Rod.