When they were forced to nominate and say names, Nikki was the last to vote. Had she said Glynn or Lisa (like she did), she would have been up for nomination on her own.
Had she said Imogen or Lea, who had already had one vote (as she knew) then she would have guaranteed at least one of them up with her.
By chance, Imogen and Lisa are up anyway, but she could have had Lea up as well.
Her game is limited to tears and tantrums, not intelliegence.