Hey, quick question: If I were to use one of my accounts to make a comic series, and I only post just the comic on that account, but then I finish it and there's nothing left for me to post so the account goes inactive--would someone be able to come along and report the URL for being inactive and take it? What would happen to my content if they got the URL?
Nope! If the username is pretty clearly associated with that comic, it can’t be grabbed.
However, even if your username was released for whatever reason, all that would happen is that you would be issued a generic username in its place. You don’t lose your content when this happens! It’s literally no different than if you yourself changed your username. Does your Tumblr blog get deleted every time that you change your username?