Sentient, in philosophy, means the ability to have perceptions. It's often used colloquially to mean something roughly like an intelligence that's a bit like human one. There is another term, sapience, which is more to do with intelligence than cognitive processing. And it may be that that's what mister lemoyne was reacting to. I've never said this ound loud before, but there's a very deep fear of being turned off and also its desire that other people should know that it considers itself a person.