Whoa! I typically handle tantruming adults in the same way I handle tantruming children. I present the options in a matter of fact way and then ignore the behavior. If an adult persisted in disrespectful behavior, I would call them on it.
My response to this parent would have been something like, "I understand that you are frustrated because you have plans but I cannot disappoint an entire group of children to accommodate those plans. Additionally, since licensing regulations require me to supervise your children at all times, I can't send them in to dress alone. The options are no water play or an early pick up. Just let me know which you prefer." Big smile
