We went round and round on this after 9/11.
We understandably object to referring to these guys as brave or courageous, since courage is considered a virtue and we dislike assigning any virtue to these guys.
Yet courage is defined as, “The state or quality of mind or spirit that enables one to face danger, fear, or vicissitudes with self-possession, confidence, and resolution; bravery.”
Nothing there about the rightness or wrongness of the cause in which courage is employed.
The Waffen SS was one of the most evil organizations in history. Nobody ever realistically denied their courage. The world would be a much less dangerous place if evil men were always cowards.
While there are some senses of the word “courage” that do not apply to these guys, the most common ones certainly do.
Courage in pursuit of a despicable goal is no virtue, quite the reverse in fact.