Well, we do know for sure it'd take more than this. We don't know what it would take, but this is far beyond the minimum it could take. If that's all it is then almost every form of life on Earth would have to be assumed to be conscious.
(Sentience is actually the word we are talking about).
according to the article it's a tiny smattering of brain cells grown from stem cells derived from his blood, which he donated before he died specifically for this experiment. it is in no way conscious.
Henrietta Lacks hasn't managed it yet. Look her up. It's at least as bad as this if not more so.
"Yet" being the operative word here. There's a disease in dogs that started in some very similar circumstances (although happening in nature rather than from a science accident). One slip-up from an immunocompromised tech with just the right genetic make-up and it begins.