I doubt the date would be changed the weekend was pick specifically not to cross over with the Brickyard 400 or Football season.
If a majority of people aren't vaccinated by August then why would anyone assume that they would be in September - November?
I obviously don't know what feedback was received but by all estimation, if you can't do it in August you probably can't do it in person at all. Hotels and airfare will become too hard to get the longer a decision takes to get made. I'd rather book for the original dates and cancel then sit in a holding pattern.
One of your original guesses nailed it.
Yes, Al has bested me. My weekends were completely off.
I surrender good sir.