Another interpretation: Scripture compared the one who slaughters to the one who sells, and the one who sells to the one who slaughters. Just as a sale is outside his domain, so too the slaughter must be outside his domain. Just as a sale leaves the animal permitted to be eaten, so too the slaughter must leave it permitted to be eaten. Just as a sale leaves it permitted in benefit, so too the slaughter must leave it permitted in benefit. Just as a slaughter cannot be reversed, so too a sale must be one that cannot be reversed. Just as a slaughter is of the whole animal, so too a sale must be of the whole animal.
Comparing the Slaughter and Sale of the Stolen Animal
Yalkut Shimoni on Torah 342:2
דָּבָר אַחֵר, הִקִּישׁ טוֹבֵחַ לְמוֹכֵר וּמוֹכֵר לְטוֹבֵחַ, מַה מְּכִירָה חוּץ לִרְשׁוּתוֹ אַף טְבִיחָה חוּץ לִרְשׁוּתוֹ, מַה מְּכִירָה מֻתֶּרֶת בַּאֲכִילָה אַף טְבִיחָה מֻתֶּרֶת בַּאֲכִילָה, מַה מְּכִירָה מֻתֶּרֶת בַּהֲנָאָה אַף טְבִיחָה מֻתֶּרֶת בַּהֲנָאָה, מַה טְּבִיחָה שֶׁאֵינָה יְכוֹלָה לַחֲזֹר אַף מְכִירָה שֶׁאֵינָהּ יְכוֹלָה לַחֲזֹר, מַה טְּבִיחָה כֻּלָּהּ אַף מְכִירָה כֻּלָּהּ.