So what if they weren't released? I remember hearing her cover of Smells Like Teen Spirit on the radio. It just seems to me a bit too much like she was trying to latch on to the popularity of 2 very well-played songs. I guarantee you some people would have started listening to her just because they originally heard 'this chick doing a cover of Smells Like Teen Spirit/Losing My Religion'. And of course she's not going to release it as a single, then she'd lose all her cool muso cred.
That said I still think it was a bit of a wanky, try-hard thing to do.
And at the risk of sounding like a stroppy little grunger, if she had any respect for the band or Kurt she wouldn't have covered a song that he hated.