Please do not. Although I don't personally want to see lolicon stuff, many of the servers willing to host it have communities I want to interact with. For instance, burggit.moe is where the touhou communities went and is otherwise a pretty nice instance aside from loli communities.

It is content which, while understandably offensive to some, harms nobody. All fictional porn, no matter how deviant it is, is ultimately more ethical than real porn can be.

It should be up to users to block or hide instances with content they don't wish to see, and defederation should be reserved for communities that consistently cause interference, not for communities that simply have content which one disagrees with.