I think there's another very big reason why usagi hasn't got a scammer tag.  Look at the record of who does and doesn't get tags - pretty much without exception tags are only awarded to people who don't ste up and attempt to defend themselves in the complaint thread against them.  As soon as they start writing long posts, making stuff up, referring to posts they've deleted etc it becomes a whole load of work to actually reach the truth.  Try to find an instance of someone who defended themselves as vigorously as usagi has getting a tag.  Sure - most of what it types is total garbage but it takes a lot of time and effort to actually become sure of that.

Another (and pretty valid) reason is that most of the complaints about usagi aren't being made by actual investors who lost money.  With the possible exception of Eskimo Bob - which is absolutely hilarious (have to wonder if he had a ton of fixed-rate mining bonds as well).  I can make a pretty compelling case of various cases of acting in bad faith, robbing one set of investors to bail out a different failed company etc - but as I didn't have any skin in the game the mods can just ignore it until someone who actually lost out complains.