How about disabling login, leaving comments in place, and also replacing all instances of the user’s name on their comments with something that looks the same but is obfuscated in such a way that it won’t turn up in searches for that name? The anonymous user who recently asked how to delete his account was specifically concerned with search results, and as a result he went through and individually deleted all his comments, which we want to discourage.
How about disabling login, leaving comments in place, and also replacing all instances of the user’s name on their comments with something that looks the same but is obfuscated in such a way that it won’t turn up in searches for that name? The anonymous user who recently asked how to delete his account was specifically concerned with search results, and as a result he went through and individually deleted all his comments, which we want to discourage.