One would be hard-pressed to find a more perfect example of doublethink than the popular notion of selflessness.

Selflessness is supposed to be praiseworthy, but if we try to clarify the meaning of "selfless person" we either get

1. A person who's greatest (or only) satisfaction comes from helping others, or

2. A person who derives no pleasure at all from helping others (not even anticipated indirect future pleasure), but does it anyway

Neither of these are generally considered praiseworthy: (1) is clearly someone acting for purely selfish* reasons, and (2) is just a robotic servant. Yet somehow a sort of "quantum superposition" of these two is held to be both possible and praiseworthy.

*The common usage of "selfish" is an analogous kind of doublethink/newspeak

ETA: I, and probably many others, consider (1) praiseworthy, but if that's the definition of selfless then the standard LW argument you mentioned applies to it.