The (alleged) sleeper's Model 3 has silver trim, so we know it's an older vintage and would therefore have radar, so it would be expected to behave differently than newer 3's with regards to the cabin camera.
I think cabin camera monitoring was recently added to radar-equipped 3/Ys as part of 2021.32.22, but (A) that video is from June, before 2021.32.22 was available, and (B), in my experience in my 2018 Model 3, the cabin camera only does anything if I'm looking at my phone for an extended period. I.e., I can have my eyes off the road, but unless I'm also looking at a phone, it won't nag me any more than normal. So it's not surprising that the sleeper's car wouldn't disengage autopilot back in June simply because his eyes were closed..
Is it even known if a radar-less 3/Y would in fact disengage autopilot with a sleeping driver (assuming his hand was resting on the wheel providing some torque)?