To be fair to him, he acknowledges that dwarfs would be the accepted version and justifies it by saying that if we talked about dwarfs or dwarves more often in regular English, we might have had a nonstandard plural for them as we do with many other common subjects. Elves also pre-dates him significantly, though I don’t doubt that he was a significant factor in it becoming the standard version. It seems there are even some examples of singular elve