Sentient is wrong, correct. "Capable of language" would be more accurate though, with the implication being that they are intelligent. Only humans are capable of language (as opposed to mere communication) and it is thought by some to be either the cause or consequence of our unique human intelligence.
Do we know that the audience understood the proposition of the pro side during the first poll? I noticed that they didn't actually explain what an x-risk is until part way into the debate. And it seems to me that some number of the public just imagine it as a general pessimism around AI, not an actual belief in a chance of extinction in 30+ years.
Since this comment got linked to, and we are throwing around anecdotal evidence, I'll add mine: the animal rights vegan club at my uni had at least one individual quite keen on supplementing (not in a wacky way, mostly commonsensical) and I didn't hear any push back from the other members. And none of them ever heard of EA. And my very leftist vegan roommate had B12 & Creatine (I assume they took them). And I assume EA is at a equal, likely higher epistemic standpoint.