In the game, Cobain's avatar has been set as a playable character, which means that he can star in any song – including even death metal and rap songs.
"While we were aware of Kurt's image being used with two Nirvana songs, we didn't know players have the ability to unlock the character," they said in a joint statement Thursday. "This feature allows the character to be used with any kind of song the player wants. We urge Activision to do the right thing in 're-locking' Kurt's character so that this won't continue in the future."
In an official statement, Activision, says Love signed a written agreement that gave them licensing rights to use Cobain's likeness for an playable character avatar.