There has to be more to this. I don't think scrubbing a rock, unless it was covered with a ton of palys, would release enough toxin into the air to hospitalize 10 and make two dogs sick. Either he boiled the rock and aerosolized the toxin, did it in a shared bathroom or kitchen and burst some onto the counter and didn't clean up or most of the people were taken to the hospital out of an abundance of caution. He could have pet the dogs without washing his hands or made dinner or something, but it's not a bomb that will harm people just taking palys out of the tank.