Why specifically the nefesh they made in Charan?

Summary: According to Rav Yonasan Eibeshitz, because they would not make any in Canaan.

Post: At the start of parashat Lech Lecha, the following pasuk and Rashi:

5. And Abram took Sarai his wife and Lot his brother's son, and all their possessions that they had acquired, and the souls they had acquired in Haran, and they went to go to the land of Canaan, and they came to the land of Canaan.		ה. וַיִּקַּח אַבְרָם אֶת שָׂרַי אִשְׁתּוֹ וְאֶת לוֹט בֶּן אָחִיו וְאֶת כָּל רְכוּשָׁם אֲשֶׁר רָכָשׁוּ וְאֶת הַנֶּפֶשׁ אֲשֶׁר עָשׂוּ בְחָרָן וַיֵּצְאוּ לָלֶכֶת אַרְצָה כְּנַעַן וַיָּבֹאוּ אַרְצָה כְּנָעַן:
and the souls they had acquired in Haran: whom he had brought under the wings of the Shechinah. Abraham would convert the men, and Sarah would convert the women, and Scripture ascribes to them [a merit] as if they had made them (Gen. Rabbah 39:14). (Hence, the expression אֲשֶׁר עָשׂוּ, lit. that they made.) The simple meaning of the verse is: the slaves and maidservants that they had acquired for themselves, as in [the verse] (below 31:1): “He acquired (עָשָׂה) all this wealth” [an expression of acquisition]; (Num. 24:18): “and Israel acquires,” an expression of acquiring and gathering.		אשר עשו בחרן: שהכניסן תחת כנפי השכינה, אברהם מגייר את האנשים, ושרה מגיירת הנשים, ומעלה עליהם הכתוב כאלו עשאום. ופשוטו של מקרא עבדים ושפחות שקנו להם, כמו (שם לא א) עשה את כל הכבוד הזה, (במדבר כד יח) וישראל עושה חיל, לשון קונה וכונס:

Rav Yonasan Eibeshitz writes, in Tiferes Yehonasan, an interesting diyuk on the word בְחָרָן:

"וְאֶת הַנֶּפֶשׁ אֲשֶׁר עָשׂוּ בְחָרָן -- For in Canaan they did not wish to accept geirim, for them to be encompassed within Arur (accursed), and therefore, even in the seven nations they did not accept, with the exception of the Gibeonites, who came with trickery. And therefore they only converted in Charan."

The idea of Canaan being arur is based on the pasuk in Noach:

כה  וַיֹּאמֶר, אָרוּר כְּנָעַן:  עֶבֶד עֲבָדִים, יִהְיֶה לְאֶחָיו.

25 And he said: Cursed be Canaan; a servant of servants shall he be unto his brethren.

and there is a nice connection drawn between the conduct of the avos and the conduct of their Israelite descendants. And it is a nice neo-midrash focused on the specification of Charan, which we can figure out anyway that that was their source location, they were obviously coming from, so why need mention it?

What gives me pause is that one can simply say that at this point in time, they were coming from Charan, where they (midrashically) made converts. They did not yet arrive in Canaan, so they could not be expected to make converts there, yet. Furthermore, what about Eliezer, who was their servant, and who descended from Canaan? Maybe there is a difference in that there were no plans to marry slaves.