Daf Yomi Brachot 18a - Accompanying a met - but how far?

On Brachot 18b, we read:

Rechava cited Rav Yehuda: Whoever sees a dead body and does not accompany it (in the funeral procession) violates Mishlei 17:5:

ה לֹעֵג לָרָשׁ, חֵרֵף עֹשֵׂהוּ; שָׂמֵחַ לְאֵיד, לֹא יִנָּקֶה.

5 Whoso mocketh the poor blasphemeth his Maker; and he that is glad at calamity shall not be unpunished.

and if he accompanies him, what is his reward?
Rav Asi said: Upon him Scriptures states (Mishlei 19:17):

יז מַלְוֵה ה, חוֹנֵן דָּל; וּגְמֻלוֹ, יְשַׁלֶּם-לוֹ.

17 He that is gracious unto the poor lendeth unto the LORD; and his good deed will He repay unto him.

{with מַלְוֵה - lender - being revowelized as melaveh, to accompany.}

The Munich manuscript of the Talmud (from 1342 - it is the only manuscript of the entire Talmud that we have today) records a variant version of Rechava's citation of Rav Yehuda, in which one is only required to accompany the dead body for a distance of 4 cubits.

This makes sense as being a formal fulfillment of escorting to provide honor to the deceased, since the minimum amount of escorting someone (such as a guest) is 4 cubits. In Sota 46b Rabbi Yehoshua ben Levi says the 400 years of servitude of Avraham's descendants in Egypt were in exchange for the 4 steps Pharaoh took in escorting Avraham - ואמר ר' יהושע בן לוי בשביל ארבעה פסיעות שלוה פרעה לאברהם.

On the other hand, I think there is a high probability that this variant reading in the Munich manuscript is the result of scribal error. After all, the pasuk cited as prooftext - לֹעֵג לָרָשׁ, חֵרֵף עֹשֵׂהוּ - was used just above, also on 18a, as a prooftext for another law:

The Sages learnt {in a brayta}: A man should not walk in the cemetary with tefillin on his head and a sefer Torah in his arms, and read in it and pray, and if he does so, he violates Mishlei 17:5:

ה לֹעֵג לָרָשׁ, חֵרֵף עֹשֵׂהוּ; שָׂמֵחַ לְאֵיד, לֹא יִנָּקֶה.

5 Whoso mocketh the poor blasphemeth his Maker; and he that is glad at calamity shall not be unpunished.

and specifically within 4 cubits, for the master said: a dead body grasps 4 cubits in terms of reading Shema, but outside 4 cubits it is permitted.

{The text marked green is part of the gemara, but is the stama elaborating upon the brayta.}

I think what happened is that the copyist's eye moved backwards to the earlier prooftext of לֹעֵג לָרָשׁ and copied the elaboration of specifically 4 cubits to the later occurrence. The Rif, by the way, has the same girsa that we have in our printed editions, without reference to 4 amot. See here, on my Rif blog.