Still doesn't explain why some of the Apple employees demoing it for the press in the hands on area couldn't get it to work reliably. I need to see more of this device tbh.
On Mark Gurman, I remember him having a piece out a few months ago claiming this FaceID tech would even work with your phone flat on a table. I was skeptical then but apparently it doesn't.
What probably happened was that the phone wasn't working properly and some on-site techs were frantically trying, failing, and handing it off to another tech; anything to get it working in time for it's stage cue. Unfortunate.