The point isn't whether the word "alimentary" means anything. You probably know related words like "alimony." (Tangentially, the humorous novel Through the Alimentary Canal with Gun and Camera is a surprising early precursor to Fantastic Voyage and related stories of microscopic explorers inside the human body.)
The point is that calling any food product "alimentary paste" is hilariously unappetizing.
'Paste' is an old word for pastry, too. It makes old recipes rather odd sounding [1]:
> make six or eight ounces of paste as No. 319, roll it to the thickness of a quarter of an inch, or a little more, put pudding-cloth in a basin, sprinkle some flour over it, lay in your paste, and then the meat, together with a few pieces of fat; when full put in three wineglasses of water; turn the paste over the meat, so as not to form a lump, but well closed; then tie the cloth
Pasta, pastry, paste, pasty. All related words. The French for pastry is pâte. Pâté means "pasted" as in "pasted fish".
The French aliment simply means food, although it's not spoken very often in France. The word exists in English but it's quite rare and normally used in legal contexts like so many other words of French origin.
https://en.wiktionary.org/wiki/alimentary
"Of, or relating to food, nutrition or digestion."
"Nourishing; nutritious."
(At least the first part; "extruded alimentary paste" would be a more precise description of noodles.)