Update: we've now heard from an attendee that they've mostly given up on participating in academic things because they are not inclusive and accessible, and thanking us for conference accessibility policy.
(In addition to requiring masking we planned for some remote participation from the get-go--and we know we will get some last-minute shifts, too.)
Anyway, we don't have to internalize & perpetuate the lousy ways our institutions treat us; better conferences are possible!