His entry "How did the word carnival come to mean a self-indulgent celebration" is a short explanation of Lent, and he only deals with the word itself in the final sentence:
In Church Latin, carne vale literally means "farewell to meat."
The OED tells us that theories like this one "belong to the domain of popular etymology" - i.e., are untrue. The real history of carnival involves metathesis. Latin carō, carnis is "flesh", and *carnem levāre is "the putting away or removal of flesh (as food)", which became carnelevārium, which became Italian carnevale, carnovale - the l and v switched places.
carō, carnis "flesh" is from a form *kar- from the Proto-Indo-European root *(s)ker- "to cut". In Proto-Germanic, this became the metathetic variants *skrap- and *skarp. *skrap- became Old English scrapian (modern scrape), and Dutch schrabbelen "to scrawl", borrowed into English as scrabble. *skarp- became sharp.