Rav Achai Gaon about a Jewish cattle middleman

On Avodah Zarah 15a, after some lengthy anonymous analysis, a sugya ends as follows:

וְאִי סָלְקָא דַעְתָּךְ שְׂכִירוּת קָנְיָא, אַמַּאי לָא יַאֲכִילֶנָּה? פָּרָה דִּידֵיהּ הִיא! אֶלָּא שְׁמַע מִינַּהּ שְׂכִירוּת לָא קָנְיָא. וְהַשְׁתָּא דְּאָמְרַתְּ שְׂכִירוּת לָא קָנְיָא, גְּזֵירָה מִשּׁוּם שְׂכִירוּת, וּגְזֵירָה מִשּׁוּם שְׁאֵלָה, וּגְזֵירָה מִשּׁוּם נִסְיוֹנֵי.

And if it enters your mind to say that through leasing one acquires the item, why can’t the priest feed it vetches of teruma? After all, it is currently his own cow. Rather, learn from here that one does not acquire an item through leasing. The Gemara comments: And now that you have said that one does not acquire an item through leasing, and therefore an animal that was leased to a gentile still belongs to the Jew, the original proposal can be accepted: The reason that one cannot sell large livestock to gentiles is a rabbinic decree due to the concern of leasing, and a decree due to the concern of lending the animal to the gentile, and also a decree due to the concern of testing.

רַב אַדָּא שְׁרָא לְזַבּוֹנֵי חֲמָרָא אַיְּדָא דְּסַפְסִירָא, אִי מִשּׁוּם נִסְיוֹנֵי — הָא לָא יָדְעָה לְקָלֵיהּ דְּאָזְלָא מֵחֲמָתֵיהּ, וְאִי מִשּׁוּם שְׁאֵלָה וּשְׂכִירוּת — כֵּיוָן דְּלָא דִּידֵיהּ הִיא לָא מוֹשֵׁיל וְלָא מוֹגַר, וְעוֹד — מִשּׁוּם דְּלָא נִיגַלֵּי בֵּיהּ מוּמָא.

§ The Gemara relates: Rav Adda permitted the owners of a donkey to sell their donkey to gentiles by means of a Jewish middleman [desafseira]. He reasoned as follows: If the concern is due to testing, in this case the animal does not recognize the voice of the middleman so that it would walk because of him. And if the concern is due to lending and leasing, since the donkey is not his, that middleman would neither lend nor lease it. Additionally, the middleman would not lease or lend the animal because he wants to sell it and does not want any blemish to be revealed in it.

Ignore the § symbol above which indicates the start of a new sugya. This is rather the culmination of the preceding sugya, in which Rav Adda* applies the ideas developed above to a practical and unique case, explaining why each reason for the rabbinic decree does not apply.

Now, plain Rav Adda would seen to be a first / second-generation Amora. Yet, he reacts to the Stammaic analysis, which I often assume to be very late. What is going on here?

The answer is that, while printings all have Rav Adda,

the manuscripts and manuscript fragments have Rav Acha or, better and mostly, Rav Achai.

As I discussed in an article a while back (but recently parked on this substack), Rav Achai in the gemara was either a one of the Savoraim who followed Ravina and Rav Ashi, or else someone even later, Rav Achai Gaon who wrote the She’iltot.

Either way, this then perfectly works as a reaction to the anonymous section. Since the gemara’s analysis concluded that the concern was a decree due to (a) lending, (b) leasing, and (c) testing, Rav Achai when faced with a novel case of a middleman, where these concerns did not apply, was able to permit.