Perhaps the moral character of the Sultansworn paladins reflects the character of whatever Sultan is in power at the time, as alluded in the OP quotes? So, for Sultana Nanamo Ul Namo, who is written to be quite just and good (Let Them Eat Cactus FATE, for example), paladins and free paladins trained under her would be rather lawful good.
Compare that to paladins under a cruel Sultan, and then they'd probably be lawful neutral.Â
All that said, I don't know if I could agree with Lawful Good for Sultansworn paladins by default (rather than varying depending on the leader)...what happens if the paladin is ordered to do an act that violates the stereotypical LG code? They -would- folllow the Sultan's orders, unless they want to surrender the paladin title (ignoring free paladins for now, since they're recent). Therefore LN is closer...
Ofc, this is using the incredibly restrictive D&D alignment system which is absolute nonsense, since you can't capture the wide range of human emotions and ideas that  single person has in one of nine labels.
Compare that to paladins under a cruel Sultan, and then they'd probably be lawful neutral.Â
All that said, I don't know if I could agree with Lawful Good for Sultansworn paladins by default (rather than varying depending on the leader)...what happens if the paladin is ordered to do an act that violates the stereotypical LG code? They -would- folllow the Sultan's orders, unless they want to surrender the paladin title (ignoring free paladins for now, since they're recent). Therefore LN is closer...
Ofc, this is using the incredibly restrictive D&D alignment system which is absolute nonsense, since you can't capture the wide range of human emotions and ideas that  single person has in one of nine labels.