I honestly didn't see the ending coming, I expected the Wub would control the others minds and eventually make it safely to Earth, leaving it's fate thereafter unknown. So that was a pleasant surprise for me, but in hindsight it does seem rather obvious.

I disagree with your last point however: the other crew members did show empathy and disgust and walked out before the killing; I would argue they only ate afterwards out of necessity under threat of starvation, but their guilt and shame over this matter were evident.

The story, to me, emphasised the "Us v. Them" mentality; the thought that one could exact extraordinary cruelty on another living being in order to ensure their own protection and survival. I imagine many of those crew members could not return to eating meat after having the harrowing experience of your meal asking not to be eaten, certainly I think the reader is intended to make that connection and question the morality of their diet and life choices.

Though maybe I'm reading too much into it...