Tosfos on 22a says that R Eliezer Hakapar and Rabanan are Cholek on the issue of Mieker Akar and Migez Gayez (being Rabanan hold by the latter) in order to explain how the Gemara suddenly changed its maskanah. This fits in very well, I think...
Rosh, however, says that you can say that R Eliezer Hakapar also holds by Migez Gayez and that the reason you don't need the Olah (if she was tmeah and then the nezirus was mufar) is that the Torah says the only time you bring the Olah for Kaparah is when she will actually go back into Nezirus. If she doesn't, because the husband was meifer, then there's no need for an Olah anymore.
How does this fit in with the Gemara on 19a that said the auther of this same braisa was R Yishmael ben Brooka? The Gemara there deliberately said that the Olah can't be brought because its only brought for Caparah, which there is no need for here (since the neder was uprooted).
Should we say the Gemarah retracted from its decision that this braisa is according to R Yishmael, and that once it decided the husband is Migez Gayez, the Gemara decided it was according to everyone? (Of-course using the Rosh' explaination that there is no need for an Olah if she enver went back into nezirus)
It seems that one does not have to say that according to the Rosh the conclusion of the Gemara is that the Beraisa of R. Elazar ha'Kapar does not agree with R. Yishmael. Rather, according to the 2nd Pshat of the Rosh, R. Yishmael continues to agree with R. Elazar but now they both hold Migez Gayez. What has changed according to the Rosh is that the conclusion of the Gemara 19a was that R. Yishmael held Meiker Akar while the conclusion of Gemara 22a is that R. Yishmael held Migez Gayez.