I only did that as a drive-by edit I believe.
Well, there are (almost) no cuisine=vegan restaurants left in OSM, because vegan is considered a diet property and not a cuisine. So you could revert, but it will likely get removed again. While I get the idea: if you tell me "it's a vegan restaurant", I already have a certain idea about what they are going to be cooking. But then, there are some specifics that your missing: it could be regional, international, macrobiotic, etc. So using the cuisine key for that nuance seems the better option to me