grammatical number - Which is correct, "neither is" or ...
https://english.stackexchange.com/questions/10304Neither belong to this Saxon's company--Sir Walter Scott, Ivanhoe, 1819; He had two job offers, but neither were ones he felt he could accept--Diana Diamond, N.Y. Times, 1974; In conclusion, it says this: The pronoun neither, then, is not invariably singular, though it is more often so.