As for branched-chain amino acids, you'll find smart people who swear that they're keto-friendly, and others who don't. One of the BCAAs, valine, can be glucogenic, meaning that it can lead to glucose production and potentially contribute to leaving ketosis behind.[1] But does that mean it will happen? Not necessarily, particularly if you're just an occasional supplement user.

While I see your point with regards to animal suffering (which is an ongoing issue), this doesn't have to be the case and on the contrary, people are more and more interested in meat from ethical sources. Watching a TED talk may be an eye opener but we should all do some research on human evolution. Your comment is biased because it only looks at one side of the argument (not to mention that some points are totally wrong, such as comparing human digestion to elephants??)