@homegrown What if I want to run an instance dedicated to the homonymous metal band, or to ancient extinct mammals, and therefore "Mastodon" doesn't hold any reference to the social network?

Sometimes I can see the argument for brand recognition, unless the brand name is a word in the English vocabulary. If you want brand name protection, then you should pick a name that isn't on the vocabulary. You can't own a vocabulary word and prevent people from using it.