Reuenthal was a prideful fool and by refusing to compromise on his pride and formally apologize and/or appeal to Reinhard, meek and impotent as that may have been, he gave Lang and Oberstein exactly what they wanted. There is a chance he would have been killed had he done what Oberstein wanted, but what's one life compared to thousands? Reuenthal got to keep his pride intact, but he threw away thousands of lives as well. The ego and politics of powerful men are more important than the individual lives under their command, just as it was when they were ruled by the high nobles that Reuenthal and Reinhard hated for their self-interested ways. One might call his actions were disgusting, and yet it's hard not to respect him. Man's pride is a powerful feeling.