Note: The Centurion Lounge is a Day of Departure lounge requiring confirmed travel plans. Passengers holding standby tickets and non-revenue standby passengers, including airline or industry employees traveling on discounted tickets, are not eligible to utilize the lounge unless they have received a boarding pass showing a confirmed seat or zone assignment for the flight for which they are on standby.
https://thecenturionlounge.com/info/...nturion-lounge
Are they enforcing this? Sound like a no go with the Amex Platinum card.