It means Britney isn't ready to be on the show yet. If she's not qualified, why did they want her? Because they're just going to use her for ratings. Britney needs to hop off Simon's Titanic mess.
No one is saying Britney "needs" this. She just had three Top 10 hits and a successful tour. JLo and Xtina were flopping and has beens. Scherzingher only had a solo career as a singles artist in the UK.