That's not what they said. They said they weren't responsible for the robot, and which is true. Same as if a human player injured another player.
The robot's operator is responsible.
I disagree, if they are running the event, they are responsible for ensuring the safety of participants. You go skydiving and the chute fails in a totally predictable way, the company who takes you up shouldn't just shrug and say, "well, we aren't responsible for the chute, that was provided by another company"