The story of Wil Wheaton being pressured off Mastodon (regardless of what you think of him; I don't think he's perfect and that's not the point) shows that there is no platform-wide defense to harassment and online mobs and showcases a way that the instance structure may be even more vulnerable to pressure. This article seems like a good discussion of some of the ways to solve that for admins. https://www.codesections.com/blog/mastodon-mobs-and-mastodon-mobs/