I don’t have the time to Google atm but there’s a growing body of experts shifting to the “it doesn’t actually matter”. Here’s a podcast about it but there are definitely more sources to find: https://www.abc.net.au/listen/programs/lifematters/the-myth-of-good-posture/13864470
I saw another comment in the thread about ensuring you get movement in – that’s what my PT hammered into me.
I don’t understand anyone here who says this lady is in the wrong. If he felt threatened or whatever then don’t answer the door? Call the police? Instead he opens the door to attack. People saying “oh that was dumb she was asking for it”, wow no.