It may perhaps be that the panel doesn't know Tiffany's last name. But she submitted a declaration in the case, and was also interviewed by an investigator (and we have the transcript), so I presume her last name is known to the parties. Plus, the opinion's all about whether defense counsel should have called her as a witness; a pretty central player.
I can't find the briefs online right now, so for now, she's simply a last-nameless "Tiffany." Someone who witnessed the defendant beating someone else up and screamed "Please do not kill my baby’s daddy” but was not called as a witness at trial.