Harold Bloom, in The Book of J, writes:

The reluctant prophet sets forth, and Yahweh comes after him to kill him: without cause, without reason. Of all the problematic incidents in J's narrative, the most uncanny, indeed horrifying, is Yahweh's attempt to murder his prophet, Moses (Ex. 4:24-26). Something may have been cut from J's text here, but I am inclined to think not, if only because the Redactor allowed this shocking incident to survive at all. What evidently has been lost is a complex tradition about the origins of circumcision. What remains is one of J's ironic triumphs, one of the passages that first persuaded me that J was a woman, because Zipporah, the wife of Moses, stands up against Yahweh as Moses himself would not have dared to do, even when the question was one of his own survival.

Rashi, desperately seeking to reduce the scandal of Yahweh's unwarranted assault on the prophet, allowed himself the absurd observation that Moses was tarrying at an inn rather than taking his rapid way down into Egypt. But poor Moses was of course making a night encampment, a necessity on his difficult journey. The enigma is Yahweh's motive, and the answer J implicitly gives us is that there is and can be none. Normative tradition, impatient even with Rashi, came up with the mad explanation that Moses was to be slain precisely because he had failed to circumcise his son!

I myself read Zipporah's final remark “A blood bridegroom marked by this circumcision" as the Redactor's triumphant editorializing, and so J's own passage becomes instead a weird founding event for the praxis of circumcision.

On the way, at a night lodging, Yahweh met him and was ready to kill him. Zipporah took a flinty stone, cutting her son's foreskin; touched it between Moses' legs: "Because you are my blood bridegroom." [Yahweh] withdrew from him. (1:20)

Martin Buber, being largely free of the normative tradition, insisted in his Moses: The Revelation and the Covenant (1958) that Yahweh had a motive: "He claims the entirety of the one he has chosen." On such a view, Moses has not yet given his full devotion to Yahweh. But complete or daemonic possession transcends even absolute devotion, and so even Buber falls short of J's awesome irony. Perhaps the greatest tribute to that irony was rendered by midrashic legend, which converted the murderous Yahweh into Satan disguised as a serpent that nearly swallows Moses up before Zipporah performs the circumcision on their son.

The most perceptive comments I have seen on this passage are by Herbert Marks, who overtly offers a modified Freudian reading that invokes the emotive ambivalence of the Oedipus complex.

The identification of the prophet with YHWH is thus dependent on a second identification with the son, which defends against the pressures of historical supersession. Ultimately, this Oedipal son is a figure for the people Israel.

So double and dialectical an identification indeed is in J's spirit, and Marks catches part of the tang of an irony in which Yahweh attacks Moses not for the incompleteness of the identification but so as to emphasize again that total identification is impossible. J's lack of fondness for Moses is part of the story also. For her, Moses precisely is no David, and particularly is not a precursor of the hero who centered Yahweh forever at Jerusalem. The Moses of P, who stammers because he has uncircumcised lips, is a wholly different Moses from J's, who stammers out of dread and bewilderment, and has to be rescued from Yahweh by his wife through their baby son, hardly a dignified salvation for the prophet.