One would simply disable propulsion and communications, and then haul the ship elsewhere for classification and sale of its cargo.
With no humans on board, then there is no incentive not to use deadly force for disabling critical subsystems.
With no humans on board, then there is no incentive not to use deadly force for disabling critical subsystems.
I suspect with drone ships and the lack of crew liability, there will arise contract security companies with pre-positioned ex-seal teams in hotspots to deal with piracy.