I'm not sure on how formally the drone pilot was involved in this because if he was and the crew were properly briefed there should be no reason for someone to throw anything at the drone. If the drone pilot did not have permission then he got what he deserved.
But, so many folks think it's OK to down a drone and car not about the cost to the owner, a cost that could be many thousands of dollars.
So, I have not idea if he was supposed to be there but if he was not permitted he has nothing to complain about even though the idea of taking down the drone is bad given the risk that it could fall on someone or the spear could hit someone.
Brian