Being German does not make one a Nazi. Many/most Christians today would absolutely denounce the actions of Crusaders (and have). Which I think was summed up well by the discussion on the first page.
The more fundamental problem I see is answering which points of doctrine and history are credible coming from a disavowed organization. --- so in other words, if the Crusaders and the leaders who sanctioned it are not Christians, then how come many Christians believe in their works. For example, they were the ones to print/copy scriptures and choose which books/passages to be added in and taken out of the bible. (they were the keepers of the faith for 300 years)
The problem seems to be that Christians can either claim to be something new, but by doing so lose credibility in what they take from history (doctrine, philosophy, scriptures), or they can hold to their history and take the baggage that comes with it. I can see why it would be a touchy subject.