Odds may be slim of there being anything newsworthy on the phone but do you think that it wouldn't be of value to the investigative team, who probably has to chase down hundreds of leads, contacts, and so forth? Unless the phone was wiped, I would be 99% confident that the team doing the actual investigation will get immense value from this phone, even if it's just tying up many loose ends.
They already had the 6-week-old iCloud backup from the device. Don't forget as well that this was a work phone, the personal phone was destroyed, which suggests there's nothing of interest on the work phone (presumably just info related to work).
