I cant play as johnny cash in guitar hero 5 wii?

So i bought guitar hero 5 for the Wii on 10-9-09. I see videos on youtube showing people playing as kurt cobain singing bon jovi. I know that people are mad about kurt cobain being used this way. I entered the all characters unlock cheat and looked for johnny cash but non of the real life artists are there. I was wondering weather the new versions of guitar hero 5 dont allow you to play as them because of the Kurt Cobain controversy or maybe the wii version doesnt allow you to play them or maybe im just doing something wrong.