I fully agree with your statement on security, I am not defending the need to learn, I am disputing the validity of the video and followup claim.
I am also not disputing the knowin issue of Twin / sibling access to devices. There is enough proof that issue exists, and I hope Apple works on tightening down the learning process to make it less of an issue.
On FaceID, I think they tried to make it a bit too user friendly and make the programming faster than TouchID. I don’t think the speed / ease should have taken priority over security.