https://www.hollywoodreporter.com/live-feed/fear-walking-dead-nick-dies-showrunners-frank-dillane-exit-1106632

Showrunner Andrew Chambliss says of Sunday's episode: "I would say the one thing we were very conscious of as we were telling these stories over two different timelines was that people would be asking questions about who's there, and who's not there. We wanted to write the stories and have them unfold in such ways that there are many twists and turns along the journey."

It was hard to tell if he was really dead the way they kept switching it around. I really hate that they actually killed him off.

Fear the Walking Dead star asked to leave the show because "the beginning of this season kind of felt like the end of an era" (http://ew.com/tv/2018/04/30/fear-the-walking-dead-frank-dillane-nick-good-out-here/)
The new showrunners didn't instigate the events of Sunday's episode.