For those that purchased at Shades of Green and the sponsor won't be able to reschedule, one option might be for the sponsor to contact SOG and convert the tickets to Magic Your Way tickets I believe the sponsor doesn't need to be present for Magic Your Way tickets (and these are still somewhat discounted and aren't taxed). Shades will also let the ticket be applied to the cost of next year's ticket if the sponsor can go in 2021/later date.
Not sure if an ITT/MWR would do the same?
Side note: Shades' Ticket office is now actively answering emails timely - DH just ordered 2 Magic Your Way tickets and he heard back within 24 hours. We were expecting not to hear several days or longer.
Edit to clarify for 2021 that sponsor must be present for Salute tickets, and also I found the page where I originally read the info:
https://www.militarydisneytips.com/...forces-salute-tickets-they-already-purchased/. Steve's site is pretty spot on.
Also, another page with good info:
https://www.militarydisneytips.com/...ces-salute-ticket-policy-for-cancelled-trips/