It's possible Honda has data suggesting reused bolts in this application have higher failure rates than new ones. Considering brakes are a safety system they may recommend replacing them out of an abundance of caution. Honda spends millions on R&D and they collect data from warranty repairs, too. It's likely a safety or legal matter rather than a financial one. If you're careful and use a torque wrench it is probably alright. But I imagine Honda mentions it for a decent reason.