I would have thought legally they would have to reopen the deadline, they had a renewal deadline then suspended sales early. I imagine there are thousands of ST holders who fully intend to renew once they have a deadline to pay by (me being one), if the club then start messing them about by moving the goalposts it has the potential to lose the club a lot of goodwill.
The only fair way is to reinstate the deadline for renewal get in all the cash from everyone who wanted to renew for next season, then have a ballot from all ST holders for each game so all ST holders who want to can see some live footy.
Edit: having read some of the above I agree they should also allow those who would attend but can't due to COVID reasons, be it them or family, to suspend their ST with the retention of privileges. Col's call for a large club survey on it to determine intentions is a good call, but time is tight and not everyone has 'opted in' for club contacts so it might prove a logistical nightmare.