To be fair, I think she does deserve a place on the panel. She's not there as a singer, but more as a representative of the "backstage" side of music: I always got the impression that she was the brains behind N-Dubz, and was very savvy in that regards.
I think that the problem is that she clearly doesn't care about the album. As people have already said, she was probably told to make a record, rather than WANTING to - she looked bored and uninterested when she finished her performance on Sunday, and it's telling that Louis was promoting her album more than she was (which - again - made her seem a bit uncomfortable). And her apathy was obviously contagious: it's not my sort of music anyway, but if an artist I was a fan of seemed like they weren't fussed out the lastest CD, I wouldn't rush to the shops for it on day one either.
Like I say, I get the impression that she is VERY savvy about the management/production/promotion side of things, it's just that she hasn't bothered at all with this album. A bit unproffessional tbh - if she wants a long-standing career doing the things she's good at, she's going to have to learn that sometimes you have to work with a product you don't necessarily love.