how could Yeshayahu haNavi resolve a machlokes Amoraim?

The second pasuk in the haftarah describes

שַׂמְתִּ֚י כַּֽדְכֹד֙ שִׁמְשֹׁתַ֔יִךְ

how the windows (according to most meforshim; see Rashi,) of Yerushalayim will be made of "kodkod."  Ibn Ezra writes that this word "kodkod"  אין רע למלת כדכד במקרא but from the context it appears to be some type of precious stone.

The gemara (Baba Basra 75a) brings an aggada to explain this strange word:

שמתי כדכד שמשותיך א"ר שמואל בר נחמני פליגי תרי מלאכי ברקיעא גבריאל ומיכאל ואמרי לה תרי אמוראי במערבא ומאן אינון יהודה וחזקיה בני רבי חייא חד אמר שוהם וחד אמר ישפה אמר להו הקב"ה להוי כדין וכדין ושעריך לאבני אקדח

There was a machlokes Amoraim, or according to a different tradition, a machlokes among the malachaim, what stones to use for the windows: shoham or yashfeh.  Hashem therefore said let it be made like this and like that, "k'dein u'k'dein" = "kodkod" in short.

Tosfos quotes Rabeinu Tam who took out this whole girsa :

ר"ת ל"ג לה ואית דגרסי ומפרשי דקאי אכתוב דלעיל הנני מרביץ בפוך אבניך ויסדתיך בספירים פירוש כדין וכדין היינו פוך וספיר דלעיל

It's not so clear from Tos what was bothering R"T, but Rashbam spells out the difficulty:

 ואע"פ שמקרא זה קדם לבני ר' חייא טובא יש לומר שכך נתנבא ישעיה שכדברי כל המפרשים עתידה להבנות:

The simple reading of the gemara sounds like there is a machlokes Amroraim what to make the windows out of, and Yeshayahu comes and resolves the machlokes "kdein u'kdein." That's impossible -- Yeshayahu lived hundreds of years before these Amoraim!  How could he resolve a machlokes that would happen hundreds of years ahead in the future? 

Rashbam solves the problem by saying that Yeshayahu was aware of the machlokes though nevudah, but R"T chose to remove the whole girsa.

I am bothered by this R"T.  To me it seems obvious that Yeshayahu is not addressing the historical machlokes Amoraim, but rather is addressing himself to the principle behind it.  Maharal in Ch Aggados basically suggests a similar hesber: the Amoraim were not arguing over what the windows were made of, but were arguing over which stone was the better stone.  Yeshayahu described the windows as made of both because there is something to be said for both views.  The same basic idea is articulated very clearly in the introduction to the Chasam Sofer al haTorah as a general principle regarding derush.  How it is possible to suggest, to take one random example, that the disagreement between Moshe and Pharoah boils down to a machlokes Rambam and Raavad -- what did Pharoah know from Rambams and Raavads?  The answer, again, is that the disagreement is over principles, and abstract principles are accessible to all people at all times. 

This presupposes that the disagreement about whether the stones used were shoham or yashfeh is not just a matter of interior design preference, but in fact reflects some deeper principle (maybe R"T did not see it that way?)  Maharal suggests that the disagreement is din vs rachamim.  Many meforshim point out that these two stones were the two stones on the choshen that represent Yosef and Binyamin.  Yosef is rescued from the clutches of Eishes Potifar because he receives a vision of his father = is'aruse dl'eila.  Binyamin is described as "chofeif alav kol ha'yom" wanting to grab back that section of the mizbeiach not built in his portion = isarusa d'letata.  See Shem m'Shmuel 5679.