Lyra would never allow Twilight to use the crown and send them both back to Equestria. Not after the years of trying to become human! She would never throw it all away! So instead, she declares herself the queen of the...pig things. Foolproof.
*apocalypse begins* Well Lyra I hope you're happy you got the crown, because now you opened the gates of hell! BUT AT LEAST YOU GOT A CROWN THAT YOU STOLE FROM AN IMPOSSIBLY CUTE...pony...pig..blob..thing..I HOPE YOU'RE F-ING HAPPY!