I don't know that it's fair to describe it as a random trivial fact; it at least
implies that he worked that shift and nobody noticed anything amiss. The events of his final day are just a tiny part of the story, but they're a part of the story nonetheless. Journalists are going to look for narratives, and the narrative of "he worked his day normally and at the end of the shift stole a plane" is different than "he wasn't scheduled to even be there that day and came in to steal a plane," or "he hadn't shown up for work the last four days, until he came in to steal a plane."
(I'm not sure the bank robber in a blue baseball hat is a good example of an unnecessary detail, by the way. Almost every story about a robbery with witnesses is likely to include basic details about what the witnesses saw. I'm not sure I've read a single story about such a robbery that wouldn't include a detail like that!)