I always like when people say "You're removing" choice with Synthesis. I mean if you went up to people and asked them "Would you like to evolve to becoming - essentially - perfect forever?" I think maybe 99.9% of people would say yes. "You're going to force me to become a perfect human? Uhm, okay, err... that's okay I think?" I think a better argument is that the bloody husk clutches its wound and becomes self-aware. That is a stronger case for why I wouldn't do it. Imagine being one of those poor sods fused to a Cannibal's arm.
I still dislike the Synthesis ending - I always pick Destroy - but I still find it a weak contrived argument for the sake of finding a moral flaw with it. This is why I dislike Synthesis actually, it's ramped up to be "the best choice" which I hate about it.