The movie did not make the German passenger out to be a collaborator or coward. It showed a passenger that wanted to seek negotiations rather than force. I can't say if the scene (a short one) was made up or not (how do you know it was made up?), but if does represent a likely scenario. Continental Europeans are more likely to take such a position.
I don't know one way or another. I just asked. Surely there were plenty of cellphone calls but I wondered where the fact and fiction line is. Surely it represents a world philosophy that was challenged by 9/11, I just thought it would be even stronger if we knew it actually happened and wasn't speculative.
The German passenger, in the film, didn't just offer to negotiate--he stood up and shouted to the hijackers that something was happening. I know that this wasn't based on research because, in connection with research I've done for a project at work, I've read every record and transcript of every phone call made from the plane. Nobody said anything about any such thing happening. As for your statement that "Continental Europeans are more likely to take such a position", I don't know, that's a mighty big generalization, based on the actions of nations rather than individuals. The real crime here is the emotional brutality visited on Christian Adams' family by the filmmakers. Given the tiny bit we know from the phone calls, there is every chance that he was a hero right along with the others.