That’s silly. I highly doubt that using #Mastodon in your name should get you in court, especially since there’s been a long-standing rock band called #Mastodon that predates the software. And it’s a word that originally refers to an animal. This frivolous lawsuit, if real, would be DOA, I’d assume.
Even, as a last resort, hiding behind parody should protect you too.
@Gargron what specific grounds were you planning on using to sue this instance?