There is a dig in ‘old and stricken’, which you will appreciate if you juxtapose Moses, who was not circumcised, and whose “natural force,” in another J document, was still vital when he died (Dt 34.7). Moses’ “natural force,” lêach, derives from lach, which means “to be moist,” or “green.” In another J document Jacob stripped rods, maqqel, which means “to germinate,” of green, lach–“to be moist,” trees to induce the animals to conceive, yâcham, and bear cattle with markings that reflect the markings on the various rods (Gn 30. 37-39, 41; 31.10). King David, who was circumcised, was old and stricken, and he “gat no heat”; ‘heat,’ yâcham, is the power to make fertile as it does in Jacob’s breeding of cattle (Gn 30.38, 39, 41; 31.10). In an effort to cure David’s impotence, for without potency a king had no might (or right) to rule, his servants delivered a young virgin, Abishag, to his bed, but the king “knew her not” in the sexual sense because he was old and stricken (1 Kgs 1). As Abraham was old and stricken and therefore could not give Sarah sexual pleasure or a child (Gn 18.10-12), King David was old and stricken, and therefore could not copulate with Abishag. When you contrast Moses, who was not circumcised but who was sexually vital until his death, with David and Abraham, who were both circumcised and impotent, Joshua, like Abraham and David, was impotent.
Like David who lost the kingship once his impotence was confirmed incurable, Joshua was unfit to lead Israel. Shortly after David was a confirmed impotent, he died; therefore we may conclude Joshua died because, for his impotence, he was no use to God.
Friedman, in The Hidden Book in the Bible, makes much of the narrative continuity of the J Source regarding giants, citing Gn 6 and Nm 13, to argue for the giants in Jo 13, but in the J documents the ‘giants’ are nĕphyil, unlike the ‘giants,’ rapha’, in Jo 13, a word Friedman, in Who Wrote the Bible, attributes to Deuteronomist 1 (Dt 2.11, 20; 3.11, 13); a word that appears elsewhere in Jo (Jo 12.4; 15.8; 17.15; 18.6),which he does not attribute to the J Source. It is unlikely that the J scribes would have used another word for ‘giant’; it is not as if ‘giant’ is nuanced.
Furthermore, in Jo 13 God said Moses gave the Reubenites and the Gadites their inheritance, which alludes to Nm 34.14-15, which Friedman, in Who Wrote the Bible, attributes to the Priestly Source. The J scribes did not allude to priestly documents, not because they did not know his work, but because the work of P was an anathema to them.
For all these reasons, besides the fact that most scholars attest Joshua is a Deuteronomistic composition, we conclude the J Source is not the author of Jo 13, with exception, perhaps, to Jo 13.1. In Friedman’s straining to make connections where there are none, he transmogrifies the J Source into a muddled document, failing to see it for the focused satire it is and was conceived to be by the sly J scribes who satirized God and the patriarchy for desecrating their goddess and persecuting her worshipers.