My co-worker was forced to retire. He doesn't look like a person nearing retirement age... is physically fit. What could be the reason?
Your company probably needed to downsize and took him on forced retirement in order to save costs of operation. He was probably chosen among the many due to inefficiency and un-productiveness.
How old is he? Some places have to force you into retirement at a certain age
Getting rid of him so that they can hire cheaper labor
Replaced with entry level pay, less or no benefits.