This is B.S.! I call shinanigans (i.e., plot hole)!
The group MC is with followed the local rules: They completely avoided damage to the island's buildings and inhabitants. All they did was attack pirates. According to what they said, that was fair game so long as neither the buildings, nor civilians, nor the local "law" enforcers were harmed. They managed to do that. The only exception is that the slave trader - worried about losing his slave shipment - bribed the local enforcers to attack them so he could retrieve the slaves (which he had not even recieved, yet). That can't even be considered stealing as they were not in his possession. Even then, MC's group avoided doing an real damage to the enforcers. It's just the ice magic froze them in place temporarily.
