It's not random, The Wanted have a history of insulting Christina in the past. Louis, being the Christina stan/diva that he is, was just doing his job: dragging The Wanted while complimenting Christina.
Lady Gaga Xtina Katy Perry Marilyn Manson Grimes
Madonna (pre 2000) J.Lo Azealia Banks Florence + The Machine Carrie Underwood Miley Cyrus MS MR
Goldfrapp Brooke Candy Ladytron The Pretty Reckless Katy B The Dixie Chicks Slayer Lana Del Rey