Sure - but it first says that these paladin will slay evil beings "only when such a deed will clearly save other lives" (emphasis added), and then it goes on to say that "some are so far along the path of evil that you have no choice but to end their lives for the greater good". Killing for the greater good is inconsistent with killing only in defence of others, unless defence of others is exhaustive of the greater good. But that doesn't seem very plausible.I don't think that there is a contradiction. Defence of others can be in the greater good.
But this is weird, too - it's a bizarre case of the game mechanics leading the fiction, and the morality of the fiction, in weird ways. ie because our default combat mechanic is "victory = reduce opponent to 0 hp", and "0 hp = dead", therefore everyone who is not a pacifist ends up having no compunctions about killing. And to have someone who takes a different view, we have to introduce this weird "knock them out and charm them" mechanic.The redemption Paladin seems more willing and capable of defending others and taking an opponent down without killing them, in order to give them a chance at redemption.
But at least as far as paladins, who tend to be melee combatants, are concerned, the new mechanic seems redundant in any event. Anyone can declare, upon dropping an enemy to zero hp in melee combat, that the enemy is unconscious - so any good character has the option of taking opponents down without killing them. And presumably that is what someone who values the dignity of other beings would do. (Eg classical knights errant spare their foes and allow them to ransom themselves for freedom, or even to be released on parole.)
I just don't get it - by stating these fairly simple moral principles as some demanding commitment of some special class, it suddenly reframes all the other paladins of devotion (who, per SRD p 33, "meet the ideal of the knight in shining armor, acting with honor in pursuit of justice and the greater good"), clerics of benevolent deities, honourable fighters etc as slavering psychopaths!