Got a reply from the person behind @mastodonanalysis

"Thank you for your note and I apologize for causing harm. As part of a class project I was trying to explore the topological structure of mastodon and identify structures for creating safe spaces in other online communities. I chose this name to alert admins to my intentions. I thought that the only harm caused by downloading data could be server overload which is prevented by API limits. The last thing I wanted to do is cause harm to your community and I have stopped downloading data."

Note that he also poses an interesting question: "It seems inevitable that someone would do this; is there anything we can do to prevent this from happening again?"