Reb Meir Eliezer - that is an excellent question. The Ritva asks your question and says that this is another reason that the Ri in Tosfos (DH Ba'i) argues with the Rashbam.

To defend the Rashbam, the Ritva proposes that the Rashbam means that after the Gemara (66a) concludes - based on the Mishnah of Daf Nachtomim - that R. Eliezer indeed holds Talush veliv'Sof Chibro is like Mechubar, it becomes evident that the words of R. Eliezer in the Beraisa of selling a house should indeed be taken literally (and " anything Mechubar is like Karka").

You might yet ask, why does the Rashbam bother mentioning this Diyuk altogether? If the clear proof of R. Eliezer's opinion is from the Mishnah of Daf Nachtomim, let it suffice for the Rashbam to cite that Mishnah (as he does in his second proof). Why must he also bring the dubious proof from R. Eliezer's statement in the Beraisa of selling a house?

The answer to this can be found in the last line of Tosfos. Rashbam is inferring from the wording of our Gemara, that the Gemara (i.e. Rav Yosef, who proposes the question in this Gemara) does indeed learn from the wording of "anything Mechubar is like Karka" that Talush veliv'Sof Chibro is Mechubar. That is why our Gemara quotes from those words of Rebbi Eliezer. In the final analysis Rav Yosef has rejected the possibility of reinterpreting those words to mean "b'Ayin Yafah Mocher."

Best wishes,

Mordecai Kornfeld

Kollel Iyun Hadaf