There is a hierarchy of 'life'. Those who try to say 'All or Nothing' when it comes to harming a sentient being are either ignorant or simply trying to justify their meat-eating habits.
You could make the same argument with eating engineered zero sentience humans. Or humans born with extreme disabilities. I think ethically it comes down to does the being have the ability to feel pain and suffer, and the emotional responses that come with it. eg a pig is more intelligent than a 3 year old, can solve the mirror test and has deep bonds with family, builds emotional connections, has the basic emotions we have etc. It's hard to justify their suffering and ultimate consumption by us when there are so many alternatives available.