Honestly, this is so trivial in my mind. With all the other problems in the world, how can you be concerned about sharing your precious recipe. Be honored anyone might want it.
I’ve spent years doing family history research for many families, and have lots of it online. I encourage people to copy it right out and share with others. That recipe won’t be any good at all when you’re dead unless you share it.
That’s MY opinion. I will hope that you will change yours, but if you don’t, then that’s ok. It’s YOUR opinion, and you’re allowed to have it.