Then what's the point of them if they are just going to go all NCR on us? Kind of ruins the whole point of the faction.
The Legion can never become like the NCR.
They're not becoming the NCR, they're becoming an actual faction that deals with people outside of their faction for reasons other than conquering them or using them to make it easier to conquer others.
The ones that disagreed with the Legion? Remember, they are Legion Remnants, not Caesars Legion.
Maybe the Legion is mostly in anarchy and this is one of the only established areas with a leader and control over their land.
They are the remainder of Caesar's Legion in the Mojave, just because the Enclave remenants didn't like how things were going doesn't mean the Legion Remenants didn't
They're probably what's left of the Legion if they're Legion Remnants and are allowed to such a meeting.