Even if there's less likelihood of useful evidence on the suspect's work phone, it's still worth checking.
The FBI's request isn't too bad really. It's not like they are requesting Apple to build a new mass surveillance tool or anything similarly far-reaching. This is limited to the domain of digital forensics, and how best to extract data in a criminal investigation, against firmware that is hostile to cracking. Given that, by design, the phone has been locked down to only accept Apple-signed firmware, then Apple is really the most feasible choice to assist in bypassing this.
The FBI's request isn't too bad really. It's not like they are requesting Apple to build a new mass surveillance tool or anything similarly far-reaching. This is limited to the domain of digital forensics, and how best to extract data in a criminal investigation, against firmware that is hostile to cracking. Given that, by design, the phone has been locked down to only accept Apple-signed firmware, then Apple is really the most feasible choice to assist in bypassing this.