Rav Nachman Speaks for Himself

In today’s daf, Bava Metzia 39a:

לְאֵיתוֹיֵי הָא דְּאָמַר רַב נַחְמָן אָמַר שְׁמוּאֵל: שָׁבוּי שֶׁנִּשְׁבָּה מוֹרִידִין קָרוֹב לִנְכָסָיו, יָצָא לְדַעַת אֵין מוֹרִידִין קָרוֹב לִנְכָסָיו.
וְרַב נַחְמָן דִּידֵיהּ אָמַר: בּוֹרֵחַ הֲרֵי הוּא כְּשָׁבוּי. בּוֹרֵחַ מֵחֲמַת מַאי? אִילֵימָא מֵחֲמַת כְּרָגָא – הַיְינוּ לְדַעַת, אֶלָּא בּוֹרֵחַ מֵחֲמַת מְרָדִין.

The Gemara answers: It comes to include that which Rav Naḥman says that Shmuel says: For a captive who was taken captive, the court authorizes a relative to descend and manage his property. If he left of his own volition, the court does not authorize a relative to descend and manage his property.
And Rav Naḥman says his own statement: The legal status of one who flees is like that of a captive. The Gemara asks: One who flees for what reason? If we say that he flees due to a tax [karga] that he attempts to evade, that is the case of one who left of his own volition. Rather, the reference is to one who flees due to an allegation that he committed murder [meradin], and he flees to avoid execution. Therefore, his legal status is that of a captive.

This strikes me as strange in two ways.

1. First, there is a general idea of ha didei, ha derabbeih, that sometimes X will cite Y saying A, and we contrast it with X saying B, and the response is that one is his citation of his teacher, while the other is his own contrasting opinion.
   
   I would have read this passage, at first, in similar fashion. That Rav Nachman cites Shmuel and agrees about point #1 (authorizing a relative to descend for a captive), but disagrees about point #2 (leaving of his own volition). Even though he uses a different word, בּוֹרֵחַ
   
   If so, the Stamma (Talmudic Narrator’s) objection, the בּוֹרֵחַ for an easy thing like a land tax is == לְדַעַת would not be an objection. But, the Stamma assumes it must be a separate case.
   
   We should investigate the usage across Talmud of דִּידֵיהּ אָמַר, a subset of these instances, in which they quote someone and then give their own position. Rav Katina gave his own contrasting reason for the earthquake in Berachot 59a; Rabbi Yochanan gives an alternate source for Notrikon, a language of abreviation, in Shabbat 105a; the third example is Shabbat 124b, where Rav Nachman (again!) cites Shmuel (his teacher) that on Shabbat, one may more a small earthenware shard in a courtyard, but not in a karmelit; and speaking for himself, Rav Nachman himself says that even in a karmelit it is permitted but not in the public domain; Rava (his student) says that it is even permitted in the public domain.
   
   We should explore the others, e.g. Ketubot 56a, where again Rav Nachman argues with Shmuel. Others might be different. But it feels like the Stamma misunderstood the meaning of dideih amar and then radically reinterpreted Rav Nachman.
   

2. Alongside this, there is a seeming shift in expectation / meaning regarding the word לְדַעַת. If you have a contrasting pair, then שָׁבוּי שֶׁנִּשְׁבָּה means against his will, while לְדַעַת is willingly. Meanwhile, despite the English translation above, it seems to tap into the meaning of ben daat, one possessing sound mind. (Yes, in terms of arriving at a new location on Shabbat outside the techum, one who takes leave of his faculties is akin to one who was forcibly transferred by gentiles. But still.) So, see Rashi, who writes:
   
   יצא לדעת אין מורידין - דכיון שהיה שפוי בדעתו ולא צוהו בלכתו לירד לנכסיו ש"מ לא ניחא ליה:
   בורח הרי הוא כשבוי - שאין דעתו מיושבת עליו מחמת שהוא בהול:
   היינו יוצא לדעת - שאין כאן בהלה: