I think the show played Phi Phi.
I think the plan was to get Alyssa to come back and eliminate Phi Phi all along. I think production knew that Alyssa would do good enough on the challenge that they could put her in top two without it looking suspicious because the challenge was in Alyssa's wheelhouse. Either Alyssa and Tatianna were both meant to win from the start or Alyssa was meant to win, but Tatianna did so good that they let her stay and split the 10k.
And with it being a comedy challenge, production knew chances were good that Phi Phi would be wearing something ridiculous when she got eliminated. Lets face it, she can come up with some stunning looks. All so she could make her exit wearing fishnets and a baby bump.