These questions are ridiculous because they conflate "intelligence" and "sentience", also known as sensory experience or "qualia". While we often have a solid epistemic foundation for the claims we make about intelligence because we can measure it. Sentience is not something that can be measured on a relative spectrum. Spontaneous emotional and sensory experience are entirely independent of intelligence and most definitely independent of an external prompt.

You are right that infants are DEFINITELY sentient, but how does that have anything to do with Lemoine's claims, or even language? Humans are born sentient and do not develop sentience or mature from a non-sentient to sentient state during infancy. We know this because despite having no language skills of their own, infants are born capable of distinguishing their parents voices from others. They can instinctively communicate their desires in the form of emotional outbursts that signal to us their potential needs or sources of irritation. Human sentience is a priori from our first sensory experience. Not one bit of learned intelligence or language is necessary for sentience, nor are demonstrations of intelligence and language sufficient evidence of sentience by themselves.

Also, what is the basis for thinking silicon-based systems and carbon-based systems have comparable qualia? This is a serious question.