I treat most players with a little caution and a lot of patience during any PUG runs and I've had parties like this that have insisted That I or another player was seriously under performing and required replacement. The simplest and quickest way to deal with any group that turns sour is either leave or in the case that you are leading, suggest that those that don't agree with your decision to stay or have the other player/s stay can leave and you will happily replace them.