@DingerX
Ian W can go on about "The Chain of Command", but it's a jet parked at the gate before the captain accepts it.
DingerX, personally I would argue if flight crew are on the deck and preflighting and pax are boarding (after confirmation from flight crew that plane is good to board), then PIC has accepted jet - and assumed significant responsibility.
This thread has demonstrated a fair bit of heterogeneity about the limits of PIC authority and responsibility. It appears likely these limits will now be defined elsewhere. There is one fundamental constant however - responsibility and authority always go hand in hand, and they will remain the opposite faces of the same coin.