I just read on the Disney Retiree site that any retiree in the park on September 2 can show their ID and be admitted to the ride. I do not know when it was first posted.
An Opportunity to Experience Remy’s Ratatouille Adventure
Bonjour! We are just a few days in to the previews for Remy’s Ratatouille Adventure and we would like to extend the fun! Now through September 2, 2021, Disney Retirees who are at Epcot® with a valid Disney Park Pass Reservation and a valid Company-issued ID will be allowed to experience the attraction.
To take advantage of this offer, please bring your Company-issed ID to the France pavilion, on the right side nearest International Gateway, and check in with an event Cast Member. As a reminder, no Guests will be allowed.
So allons-y – let’s go ride Remy’s Ratatouille Adventure!