I don’t quite get your point. Even if a steel-frame bicycle (or for that matter, underinflated tires) would give the boss a better workout than his high-efficiency fancy carbon fiber bike, he could still be perfectly correct that combining his exercise regimen with his commute worked out to be a net time-saver for him.
E.g., if his daily commute would be a half-hour by car but an hour by bicycle, and if driving to work meant that he would spend an hour daily on a different exercise program, then clearly he’d be spending 1 hour per day on the combination of commuting and exercising if he biked to work, compared to 1.5 hours per day if he drove to work. I don’t really see how the cost or composition of his bicycle affects that calculation in any way.