The sneak.berlin instance is a small or single-user instance operated by a software author who writes hostile instance-scraping bots. On the web page for that software, in the ironically named "ethics statement", he writes:
Publishing your toots/messages on a server without marking them private or requiring authentication and thus making them available to the web is an act of affirmative consent to allowing others to download those toots/messages (usually by viewing them in a browser on your profile page). If you don’t want your toots downloaded by remote/unauthenticated users on the web, do not publish them to the web.
If you publish them to the whole web (and your home instance serves them to all comers), do not be surprised or feel violated when people download (and optionally save) them, as your home instance permits them to.
This is an interesting take on online privacy, to be sure: "because you have not physically restricted me from harvesting your information, you are affirmatively consenting to it". This is much the same argument as "you shouldn't have let me hit you" and carries about the same moral weight with me.
By choosing not to talk to this instance, I hope we make clear that the Free Radical community does not wish to interact with the author or his software.