Re. the "sentient snakes": I had a similar reaction, "What, snakes in this world are intelligent, and that has no consequences?" But centering the reaction on moral issues... well, this is a gripe/rant/sore spot with me. Particularly when the word "sentient" is involved.

"Sentient" means the ability to feel. I don't know if snakes are sentient. But I absolutely guarantee you that cows and pigs are sentient.

In moral debates, the word "sentient" is one of a class of words I call "words that don't mean what they mean": words that we systematically abuse, by having 2 definitions; and we use the word in practice with definition 1, and pretend it has definition 2 when we want to justify our actions.

It is so very very common for people to talk about "sentient life", and use it to mean "life forms with a grammatical language". If you just came out and said, "I think that the feelings of beings that can't express themselves with a recursive grammatic structure need never be considered", people would realize how unjustified and self-serving this view is. So people use the word "sentient", yet in a way implying it applies only to beings with grammar, so they can say what they want to say, but in a way that sounds like they are saying something less self-serving.