A good question, one of those things I assume is clearer than it is.
In some cases, a new body needs to be made. Pohatu’s body wasn’t that badly damaged, but the Starbrain put it down as “new body” since he wasn’t sure if anyone would be there to bring the body to the revival machines.
I would have stated it more directly in the story, but I wanted it to be more of a reveal when New-Pohatu shows up.