As per LoungeBuddy you are incorrect, but than again, they could be wrong
You must have misread LoungeBuddy.
https://www.loungebuddy.com/blog/airspace-lounge-ultimate-guide/American Express Platinum Card and Centurion Card Members
AMEX Platinum and Centurion Card members have free access to Airspace Lounges,
and are allowed to bring up to two guests each into the lounge.And directly from Americanexpress.com
https://www.americanexpress.com/us/credit-cards/benefits/detail/the-lounge-collection/platinum"Keep in mind that each program in The Global Lounge Collection has its own guest policies:
The Centurion® lounge network
The Centurion Lounge: Platinum Card® Members may bring immediate family (spouse or domestic partner and their children under 18) OR up to two (2) companions in with you.
The Centurion Studio: Platinum Card® Members may bring immediate family (spouse or domestic partner and their children under 18) OR one (1) companion in with you.
Airspace Lounge:
You can bring two guests with you at no additional cost. To bring any additional guests, you'll be responsible for the guest fees, which vary by location."