It just dawned on me that they would know the Apache lied if they wanted to. No nose could have verified it easily. They might have just gone along with it as a good idea. Something along the lines of we did offer to fight them for honor. We set our terms and they don't want to fight us. We are more powerful and could kill them if we want to but we have a bigger common enemy... so we're going to let it slide because were bigger, tougher AND smart :)

Oops. I didn't take into account the other Apache tribes. Still it does seem that overall they kept it small between the 2 groups not wanting to blow it up to the entire larger tribes/nations.