They won't offer Squirrel in stores unless there's enough demand for it.
From the link-
"While there are times when a squirrel is safe to eat, you should never try to kill one and eat it. The ODNR has guidelines to protect you and your family from eating an injured squirrel. Those guidelines are important to remember when preparing squirrel meat in your kitchen. You should avoid butter or cream based sauces, as these can harm the animal. Instead, use a beurre sauce, and if possible, a mix of veal or beef stocks. Finally, don’t use dark liquor when cooking a squirrel."
Read our latest post on " Odnr When Not To Eat A Squirrel ''. Do enjoy it Odnr When Not To Eat A Squirrel
Also, from the second link,
"Can you eat squirrel?
Yes, in general, squirrel meat is safe to eat and delicious. It’s said to taste a little like chicken or rabbit, with a distinctly nutty flavor. The meat is finely textured, lean, and light in color.
However, you must take some precautions to eat squirrel safely."
Most of us see squirrels either as cute and entertaining or destructive pests. However, to starving survivalists, they're a great source of protein and nutrition. Can you eat squirrel? Yes, in general, squirrel meat is
"Them's good vittles"- Jed Clampett
Not saying I'm gonna do it, but it seems that you're position that 'Squirrels aren't used for food' isn't quite correct.