What remembrance events took place on Saturday night that he should of been at instead
Um...the Festival of Remembrance, at the Albert Hall, attended by the senior royals.
Plus, you are aware of the time difference between California and the UK? Harry's partying was happening just a few hours before the ceremony at the Cenotaph, also attended by all senior royals.
This isn't a good look for Harry, whether he's wearing a poppy or not.