Passing in a double yellow is entirely irrelevant in this case. At fault driver was traveling same direction, there was no oncoming traffic, the road was straight and level with clear visibility. Whether some government goon decides to paint solids or a stripe makes no difference. It was a safe pass from what I can tell. Personally I don't pass when not legal, but legality has nothing to do with safety or in this case fault and liability for compensation of monetary and other damages.
Whether there was a wasp or spider as the at fault driver has claimed is also irrelevant. The man did not maintain control of his car. If if was a legal passing zone the outcome would have been the same. If there was a compact car full of infants coming the other direction at that moment the outcome would have been essentially the same but with a different set of victims. This guy failed to maintain control of his vehicle and caused property damage and injury to someone. He must make the motorcyclist and his passenger whole financially and compensate them appropriately for injuries and wasted time from this. If his actions were intentionally and malicious then perhaps he should be put in jail to protect the rest of us.