I am a lawyer. Reimbursement for ingredients or other expenses is not selling homebrew. The fact that this is a corporate-type entity is significant, because corporations are not prohibited from homebrewing, that I know of. As a very general rule full of exceptions, anything an individual can do, a corporation (particularly a nonprofit) can also do. So ingredient-reimbursement within the same CSA would be legally akin to my buddy paying for the ingredients for one batch and me for the next and us sharing both batches.
That being said, it does sound like this CSA may be selling homebrew because of the "optional donations." Regardless, I would be shocked if the SFDA wanted to prosecute this CSA, and I seriously doubt the ATF is going to pick this one up, so it is "legal" in the sense that no one is going to be enforcing the law. California also has about the most lax alcohol sales and distribution laws around, fwiw.