Mandalore has to fight Kun if he challenges him. If they fight, Kun wins with ease. If Mandalore refuses, his soldiers lose their respect and faith in him as a leader. Now the Mandalorians are fighting each other to decide a new leader. Kun takes advantage of this and systematically wipes out the Crusaders, just like he was doing with the Jedi.
I would disagree. According to the Resol'nare
- the tenets of the Mandalorians - the Mandalorians had to obey their Mandalore, no matter what the situation. Anyone who failed to follow the tenets would be declared dar'manda
, which much like 'Mad Claw' in Wookiee culture, was tantamount to a curse. Dar'manda
were considered soulless and had no place in the Mandalorian afterlife, they were not Mandalorians at all.
So to turn against Mandalore would be to reject your culture and condemn yourself to hell - no Mandalorian would want this. The Mandalorians were not Sith, they were not plagued by infighting and were extremely dedicated to their leader. Neither were they stupid, they would see the wisdom in Mandalore's decision, going against a Sith Lord in single combat would be foolish - they wanted to win. The only way a Mandalorian could challenge the leader was by seeking one on one combat himself, and seeing as Cassus Fett and Canderous are out of the battle, no one would be worthy.
Challenging Mandalore is simply not an option.