The post doesn't say he was "renamed," just says he will be "referred to" as Grommash. Furthermore, I wouldn't go too crazy over how someone phrases things in English if it isn't their first language. It's kind of the same reason a lot of people dismissed the NGA admin's leak as gibberish when the hints he dropped were poorly translated.
I think people expect leaks to be long, elegant posts that are detailed and infallible, when often a leak would be something that's obtained second-hand and on-the-fly. The former is a fantasy that a lot of people here like to make up and speculate about, which is fine.