To the issue of akrasia, I don't see this as a case. My own judgement says that a life like theirs is vapid and devoid of meaning. Fighting to the death against one's own best judgement probably isn't rare either; I expect many, many soldiers have died fighting wars they despised, and who had options other than fighting them. In effect, I feel like this is multiplication by zero, and add infinity. You have more at the end; you're just no longer the unique complex individual you were, and I could not bear to submit to that.

It really does seem like either you don't really believe that the assimilation ending is optimal and you prefer the true ending, or you are suffering from akrasia by fighting against it despite believing that it is. You haven't really explained why it could be anything else.