It sounds like you've already given your DD the best advice I have to offer to you: "those things are not always in our control." You can tell someone something, but you can't make them learn from it. Since this guy felt it necessary to say he's a "trained mediator," he probably isn't going to accept feedback on his mediation methods from a parent. So, he'll have to live and learn, instead.
I see a silver lining here. The teacher is mindful enough of the pitfalls of group projects that he put in a tracking mechanism for individual efforts, and once he found out your DD has been doing all her group's work, he shut her down. At least she won't get stuck doing all the work and the group getting all the credit.
