General Contractors Workman's Compensation Insurance Exemption, but when the GC is injured, Who Pays?

We have a Condo complex and HOA, an owner hires a General Contractor to install a dishwasher. That General Contractor because he contracts with his brother as his partner, claims a Workman's Comp Exemption. He gets injured some how absent of witnesses and now wants to make an insurance claim to the Condo HOA. The HOA didn't hire him and the Condo owner assumed he had insurance! According to the state of California he is licensed, a Building Contractor and is bonded. Can he hold the HOA responsible for an injury while contracting with a owner of one unit of 40? The HOA did not enter a contract with this guy, who has exempted himself from WC Insurance?