Bummer.
I keep hearing about the poor guy/family who gets there and gets turned away, and that's why we can't have temp checks or anything else. Where will he go? Can't get on a bus, can't have a room? (Doesn't stop the hospital I work at from telling everyone they can NOT work if they don't pass the temp check, my department head had to sit in the shade for 10 minutes before they let her in, BUT I Digress)
Anyway, it seems to me the only reasonable way to avoid this calamity (although they are gonna have to deal with it SOMEday) is -
all reservations for those coming to WDW now have to be accompanied with an email or fax showing that all parties arriving have been tested and are negative. All parties are to have their confirmations done at least a week in advance, or your ressie is cancelled. This should include day trippers, who go online (just like every other thing you have to go online for at WDW) "this/these are day/days I wish to come", get assigned a number, and send in their paperwork on time.
If you show up at the toll plaza and you can't show that your reservation with neg confirmation, you are turned away- no test, no nothing, goodBYE Felicia. Thus Disney is not responsible for whether or not you showed up positive or feverish or whatever. You were supposed to be cleared before you arrived, the burden is on the applicant, not the place.
Hey, my idea may be crazy or not, but that's what I would do, in their place. Prior Clearance Rezzies ONLY.