The post acceptance factory fly-by was always a 'thank you' to the people who built the aircraft and gave them,and the accepting airline, a chance to see and take pride in the end product in its natural environment.. and to say goodbye.
Shame that this Captain didn't just fly an approach to a 50ft go-round with an early turn away. It would have been just as impessive and not a word would have been said. SOP's would have been followed, too. Then again, SLF may have felt something happening, unlike this flyby ...........