Correction: The Rashbam said that the text does not say "v'Od", for this v'Od (i.e. the Heter that Rebbi gave) refers to the matter [taught just] above. (V'Od connotes that it is a new matter.)

Citation (Tosefta 4:16): A case occurred in which an old shepherd came in front of Rebbi and said "I remember that people of Migdal used to descend to Chamsan, to the outer Chatzer near the bridge", and then it says that Rebbi permitted people of Geder...

Defense (of our text): However, it is written in a [version of the] Tosefta, after the shepherd's testimony, "Rebbi permitted people of Migdal to descend to Chamsan, until the outer Chatzer near the city";

Now, it is fine that it says v'Od (further), Rebbi permitted people of Geder, since above it discusses Rebbi's Heter for people of Migdal based on the shepherd's testimony.

Alternative text: R. Chananel's text says "and also this Rebbi permitted..."

Explanation #1 (Rashi): Chamsan (was shaped like a bow), and there were more than 4000 Amos between its ends. It says above (55a) that they measure for it from the bow. The Techum of the people in the bow ended at the [closer] end of Geder, and they could not enter it;

However, people of Geder may descend to Chamsan, for we measure for [people of] Geder from their wall, and all of Chamsan was enveloped within their Techum.

Objection: His Perush is astounding! If people of the bow are enveloped within the Techum of Geder, if so also they are permitted to ascend to Geder!

Suggestion: Perhaps he refers to people at the ends of the bow. They are enveloped within the Techum of Geder.

Rejection: Still, whenever it is permitted for these, it is permitted for these! People of the ends of the bow and people of Geder may come to each other. People in the middle of the bow and people of Geder are both forbidden to [come to the place of] each other.

Explanation #2 (R. Tam): Geder was shaped like a bow. There were not 4000 Amos between the ends. We measure for it from the Yeser. Therefore, they may come to Chamsan;

However, people of Chamsan cannot ascend to Geder, to the middle of the bow;

It is possible that even from Chamsan to the ends of the bow of Geder was more than 2000 Amos, and even to there they could not go.

Explanation: This is because we hold like the lenient opinion in Eruvin, like Rashi explained, and Techumim is mid'Rabanan, like I explained above (46a).

Inference: R. Eliezer ben Yakov refers to both Nochrim and Kusim.

The Gemara explains that R. Eliezer ben Yakov's reason is because Nochrim are suspected of murder. With two [Yisraelim], it is common to live with [Nochrim], Chachamim decreed about them, lest one learn from [a Nochri's] deeds...

Question: Kusim are not suspected of murder, and not of bestiality or homosexuality, like is proven in Avodah Zarah (15b). One may leave an animal in an inn of Kusim, and one may be secluded with them. If so, it is common to live with them. Chachamim should have decreed (even about one Yisrael living with them)!

Suggestion: R. Eliezer ben Yakov holds that Kusim are Gerei Arayos (their conversion was invalid, for it was only so that the lions would not eat them), and they are suspected.

Rejection: Even according to the opinion that they are Gerei Arayos, they are not suspected, for it asks there from a Beraisa that forbids selling small animals to Kusim, and wants to prove from this that the reason is because they are prone to sell to Nochrim, and not because they are suspected;

Why [did the Gemara think that this is a proof]? Perhaps they argue about whether Kusim are Gerei Arayos or Gerei Emes!

Answer (Ri): The primary enactment was due to Nochrim, lest one learn from his deeds, and not due to a Tzeduki or Kusi;

Since they forbade Nochrim, they forbade also a Kusi. Since he is forbidden only due to Nochrim, they were not more stringent about them than about Nochrim.

Explanation: He holds that a Tzeduki is not like a Nochri, like the Gemara explains.

Explanation #1 (Rashi): He agrees that a Kusi is like a Nochri, because they are Gerei Arayos.

Implied question: The first Tana who forbids regarding a Kusi, this is R. Meir, like it says in the Gemara, and we know that he holds that they are Gerei Emes, in Bava Kama (38b), and even so, he forbids regarding a Kusi!

Answer: Even so, Rashi needed to explain R. Gamliel's reason due to Gerei Arayos. This is because it is fine that the first Tana does not distinguish between a Tzeduki and a Kusi, and he forbids a Tzeduki, even though he is a full Yisrael, and the same applies to a Kusi...

However, R. Gamliel, who distinguishes between a Tzeduki and a Kusi, you are forced to say that this is because a Tzeduki is a full Yisrael, and a Kusi is a full Nochri, for they are Gerei Arayos.

Question (Ri): It explicitly connotes in Gitin (10a) that R. Gamliel holds that Kusim are Gerei Emes, for he is Machshir a Get with two Kusi witnesses!

Strengthening of question: It says in Chulin (5b) that R. Gamliel and his Beis Din voted about the Shechitah of Kusim and forbade it. It explains there the reason, because they hold like R. Meir, who decreed about their wine, because it was found that they have the image of a dove [that they worshipped], and he was concerned for the minority (who are idolaters).

This teaches that they are Gerei Emes. If they were Gerei Arayos, he would not need to decree about them. Automatically they are forbidden!

Answer #1 (Rashi): That R. Gamliel was the son of R. Yehudah ha'Nasi. (Here, we discuss R. Gamliel the grandfather of Rebbi.)

Objection #1: This is astounding. Everywhere, [R. Gamliel the son of Rebbi] is called R. Gamliel bar Rebbi or R. Gamliel Beno Shel R. Yehudah ha'Nasi! (Stam R. Gamliel was Rebbi's grandfather; he was Nasi in Yavneh.)

Objection #2: It is impossible that R. Meir, who was before R. Gamliel bar Rebbi, decreed about their wine mid'Rabanan, and neglected (did not decree about) Shechitah mid'Oraisa, that R. Gamliel bar Rebbi needed to decree about it!

Objection #3: It is totally unreasonable that if he decreed about their wine due to Yayin Nesech, that their Shechitah would be permitted, since they are considered like wanton idolaters!

We say in Chulin (5a) that a Mumar to idolatry, one may not eat from his Shechitah!