I was on the survivor team when this happened, and no one told the infected this was going to happen. The survivors were losing so they all wanted it to end quick and said nothing about it. I don't know why she slayed the infected twice. People on the infected were saying it was abuse and it does sound like it. But as she said in the screenshot, she tried to balance it by giving the infected points. But at this point I got kicked for my ping and didnt witness the dodgeball part.
On a side note, I really need to make a habit of demoing whenever I play.