I don't understand the risk of being kicked out of the flight for the AUH-bound flight if you have a BP with a seat number. It means that this seat was available or that the previous occupant was moved to another seat. Otherwise, would you have been on standby, you would have a BP without seat assigned and a SBY sign or equivalent. IMHO if you have a BP with a seat number, you're good to go.
Please report here and I wish you good luck