The word shi, "departing," may very well be understood in the sense of dying.
The word fan means literally "return," denoting "coming back," and in order
to imitate the terse Chinese text, the best translation for "having come back" is "home." Lao-tze says: "Reason, the great distant beyond, is our home."
Section 5 seems to be a gloss which slipped into the text. At any rate the bracketed portion is too trivial to come from the hand of Lao-tze.