I really love Tulisa's song, but it was obvious to most sane people that it wasn't going top 10. A lot of people don't like the song, and it's urban-styled, which means it'll do worse in the charts. Amelia's song is dance-styled, so obviously it will do better. Amelia would also miss the top 10 if she released an urban-styled song.
A lot of artists like Nicki Minaj who do songs similar to Live It Up don't even bother releasing them in the UK, for the reason that they know they won't do well here. I'm glad Tulisa used it as a single though, since I really love the song, it's much better than Young imo.