What makes you think that the reason of the Talmidims was rejected? Rebbi Shimon agreed that the Jews in Shushan were guilty of having benefited from the feast, he only objected to extending that reason to the Jews outside Shushan. In fact, Rashi in the Megilah (4:1) cites both reasons.

You may wonder why the punishments of the Jews in Shushan and the other Jews were the same, if their sins were different. The Kollel addressed that issue in their Insights to the Daf on this Daf, included below.

Wishing you a Freilichen Purim,

Eliezer Chrysler

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Megilah 12

1) WHY WERE THE JEWS DESERVING OF PUNISHMENT?

QUESTIONS: The students of Rebbi Shimon bar Yochai suggested that the Jewish people were threatened with annihilation in the times of Haman because they sinned by partaking of the banquet of Achashverosh. Rebbi Shimon bar Yochai asked that if this was the cause for being punished with such a threat, why were the people outside of Shushan -- who did not partake of the banquet -- also threatened with annihilation? Rather, Rebbi Shimon bar Yochai explained that the Jewish people were punished because they bowed down to an idol during the reign of Nevuchadnetzar. His students countered that if that was their sin, why did they deserve to be saved through a miracle in the times of Purim? Rebbi Shimon bar Yochai answered that since they did not actually worship the idol but merely made it look as though they were worshipping it (in order to avoid harsh repercussions), Hash-m punished them by merely making it look as though they were going to be destroyed.

Why did the students ask this question only on the explanation of Rebbi Shimon bar Yochai? Even according to their own explanation (that the people sinned by partaking of the banquet of Achashverosh), the Jews did not deserve to be saved.

Moreover, what was the basis for their question in the first place? Perhaps the Jewish people repented and that is why they deserved to be saved. Genuine Teshuvah saves the sinner even if he actually sinned, and certainly when he merely gave the appearance of sinning.

ANSWERS:

(a) RAV TZVI ELIMELECH of Dinov (in REI'ACH DUDA'IM) explains that when a person sins his form of repentance must correspond to the sin he committed. In the case of Purim, the Jewish people repented by fasting for three days. If their sin was that they participated in the feast of Achashverosh, it is logical that they repented by fasting for three days. They were saved as a result of their repentance. However, if they sinned by bowing down to an idol, repentance by fasting would not have corresponded to their sin and would not have been a proper form of Teshuvah, and the people would not have deserved to be saved. For this reason, the students of Rebbi Shimon bar Yochai did not accept his explanation of how the people sinned.

(b) Another answer may be suggested based on the commentary of the VILNA GA'ON and others (see ABARBANEL, YOSEF OMETZ, MALBIM) on the verses in Esther (3:12-14) which describe the messages that Haman sent to all parts of the empire. The first verse (v. 12) relates that Haman sent letters to the Achashdarpenim (satraps) of the king and to the Pachos (governors) of each province. In this letter, Haman wrote that they should destroy all of the Jews on the thirteenth day of the twelfth month (v. 13). The verse (v. 14) then repeats that a "synopsis of the writing was to be given out as a decree in every province, [it was to be] revealed to all the peoples that they should be ready for that day."

The verses imply that Haman sent two different letters -- one to the rulers and another one to all of the people. What were the contents of these two different letters?

The commentators explain that Haman was afraid to send an open letter -- for all to read -- with a proclamation that the Jews should be killed on the thirteenth of Adar, because such a public announcement would warn the Jews to his intentions and enable them to find some way to thwart his plan. He therefore sent a detailed letter only to the rulers of each province, telling them that the Jews were to be killed on the thirteenth of Adar, and that the plan should be kept secret until that day. However, he also needed to notify the population at large to prepare for battle, since they could not be notified at the last minute in a kingdom as large as Persia. He therefore sent out a public letter, warning all of the people to be prepared for battle on the thirteenth of Adar and to attack whomever the leaders tell them to attack. The Megilah calls the first letter the "Devar ha'Melech" ("the [private] word of the king"), and it calls the second letter the "Das ha'Melech" ("the decree of the king").

This explains why the verse later (4:3) says that "in every province -- wherever the word of the king and his decree reached -- there was great mourning for the Jews." Why does the verse say, "in every province -- wherever the word of the king... reached"? It should say, "in all provinces, there was great mourning for the Jews." The answer is that in many provinces of the empire, the Jews were not in mourning because they did not know what the confidential "Devar ha'Melech" said, and they had no idea who was going to be attacked. Only in specific provinces, where Jews held positions of prominence and were privy to the classified information contained in the "Devar ha'Melech," did the Jews mourn because they knew about the terrifying contents of the "Devar ha'Melech" as well as the "Das ha'Melech." When Esther begged the king to rescind the decree, he allowed her to send out a new proclamation to replace the first letter; the new proclamation declared that the people should battle and destroy not the Jewish people, but the people of Amalek.

According to this explanation, the Jews outside of Shushan were not aware of the edict to kill the Jews, and thus they obviously did not know that they needed to repent for any sin. The people in Shushan, however, found out about the contents of the edict through Mordechai, and thus they embarked on a major campaign of Teshuvah.

This was the question of the students of Rebbi Shimon bar Yochai: if the Jews were being punished because they participated in the banquet of Achashverosh, then only the Jews in Shushan deserved to be killed. They were spared because they repented. Rebbi Shimon bar Yochai asked that the sin of participating in the banquet could not have been the cause for the threat to the Jews outside of Shushan (who were also threatened with destruction), for they did not participate in the banquet. It must be that the threat of destruction was a punishment for all of the Jews from all of the provinces for their sin of bowing down to the idol in the times of Nevuchadnetzar. However, since they committed that sin only out of fear and not with genuine intent to worship the idol, Hash-m punished them by merely frightening them; He never intended to carry out the threat and let them be killed.