I'm having trouble seeing the relevance of either of those posts. Elga's article is about static self-locating belief, i.e., which of two individuals I should believe myself to currently be. Eliezer seems only to be questioning the coherence of dynamic self-locating belief, i.e., which individual I should believe to be my future self. And I'm not presently sure how the Boltzmann Brain post touches on this at all.