I'm not really sure what "backup plans" they NFL could have instituted? Co-locate all players and team personal in temporary house for 8 months?
It's obvious NFL is going to blame team/players. At the end of the day the players/coaches/teams/NFL want to get paid so they will solider on, unless someone dies.
I know the schedule is made months in advance, and typically takes into account a whole host of other dates/events happening at NFL facilities and other sports etc (but this is only happening at extremely low rates now, and NFL obviously still have 1st right), but another option is to kill the current schedule, and expand the season by 2-3 weeks, and maybe play 12 games per week, the revised schedule is released every Tuesday for the Thursday/Sunday/Monday slate of games. Any team with active non-contained infections are shelved for 2 weeks.