It actually is possible, but yeah... ppl who can do this don't really care :\seemed like this was happening some months ago i saw some promising news in a few posts a while back but nothing has ever materialized
as far as i remember it patches the function that checks the signatureif CBHC could prevent the format message, I guess Ustealth would be useless.
I don't know how Mocha is doing it (preventing the partition table to be checked, or faking it as WiiU HDD, result is the same but approach is different)